Prepare for separation of RSpec helper files

Since rspec-rails 3, the default installation creates two helper files:
* `spec_helper.rb`
* `rails_helper.rb`

`spec_helper.rb` is intended as a way of running specs that do not
require Rails, whereas `rails_helper.rb` loads Rails (as Discourse's
current `spec_helper.rb` does).

For more information:

https://www.relishapp.com/rspec/rspec-rails/docs/upgrade#default-helper-files

In this commit, I've simply replaced all instances of `spec_helper` with
`rails_helper`, and renamed the original `spec_helper.rb`.

This brings the Discourse project closer to the standard usage of RSpec
in a Rails app.

At present, every spec relies on loading Rails, but there are likely
many that don't need to. In a future pull request, I hope to introduce a
separate, minimal `spec_helper.rb` which can be used in tests which
don't rely on Rails.

spec/controllers/admin/admin_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::AdminController do
 

spec/controllers/admin/api_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::ApiController do
 

spec/controllers/admin/backups_controller_spec.rb

@@ -1,4 +1,4 @@
-require "spec_helper"
+require "rails_helper"
 
 describe Admin::BackupsController do
 

spec/controllers/admin/badges_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::BadgesController do
 

spec/controllers/admin/color_schemes_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::ColorSchemesController do
   it "is a subclass of AdminController" do

spec/controllers/admin/dashboard_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 require_dependency 'discourse_version_check'
 
 describe Admin::DashboardController do

spec/controllers/admin/email_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::EmailController do
 

spec/controllers/admin/embeddable_hosts_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::EmbeddableHostsController do
 

spec/controllers/admin/embedding_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::EmbeddingController do
 

spec/controllers/admin/emojis_controller_spec.rb

@@ -1,4 +1,4 @@
-require "spec_helper"
+require "rails_helper"
 
 describe Admin::EmojisController do
 

spec/controllers/admin/flags_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::FlagsController do
 

spec/controllers/admin/groups_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::GroupsController do
 

spec/controllers/admin/impersonate_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::ImpersonateController do
 

spec/controllers/admin/permalinks_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::PermalinksController do
 

spec/controllers/admin/plugins_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::PluginsController do
 

spec/controllers/admin/reports_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::ReportsController do
 

spec/controllers/admin/screened_emails_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::ScreenedEmailsController do
   it "is a subclass of AdminController" do

spec/controllers/admin/screened_ip_addresses_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::ScreenedIpAddressesController do
 

spec/controllers/admin/screened_urls_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::ScreenedUrlsController do
   it "is a subclass of AdminController" do

spec/controllers/admin/site_customizations_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::SiteCustomizationsController do
 

spec/controllers/admin/site_settings_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::SiteSettingsController do
 

spec/controllers/admin/site_texts_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::SiteTextsController do
 

spec/controllers/admin/staff_action_logs_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::StaffActionLogsController do
   it "is a subclass of AdminController" do

spec/controllers/admin/user_fields_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Admin::UserFieldsController do
 

spec/controllers/admin/users_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 require_dependency 'single_sign_on'
 
 describe Admin::UsersController do

spec/controllers/admin/versions_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 require_dependency 'version'
 
 describe Admin::VersionsController do

spec/controllers/application_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe TopicsController do
   before do

spec/controllers/badges_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe BadgesController do
   let!(:badge) { Fabricate(:badge) }

spec/controllers/categories_controller_spec.rb

@@ -1,4 +1,4 @@
-require "spec_helper"
+require "rails_helper"
 
 describe CategoriesController do
   describe "create" do

spec/controllers/clicks_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe ClicksController do
 

spec/controllers/composer_messages_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe ComposerMessagesController do
 

spec/controllers/directory_items_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe DirectoryItemsController do
 

spec/controllers/draft_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe DraftController do
 

spec/controllers/email_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe EmailController do
 

spec/controllers/embed_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe EmbedController do
 

spec/controllers/export_csv_controller_spec.rb

@@ -1,4 +1,4 @@
-require "spec_helper"
+require "rails_helper"
 
 describe ExportCsvController do
   let(:export_filename) { "user-archive-codinghorror-150115-234817-999.csv.gz" }

spec/controllers/groups_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe GroupsController do
   let(:group) { Fabricate(:group) }

spec/controllers/invites_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe InvitesController do
 

spec/controllers/list_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe ListController do
 

spec/controllers/manifest_json_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 RSpec.describe ManifestJsonController do
   context 'index' do

spec/controllers/notifications_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe NotificationsController do
 

spec/controllers/omniauth_callbacks_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe Users::OmniauthCallbacksController do
 

spec/controllers/onebox_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe OneboxController do
 

spec/controllers/permalinks_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe PermalinksController do
   describe 'show' do

spec/controllers/post_action_users_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe PostActionUsersController do
   let!(:post) { Fabricate(:post, user: log_in) }

spec/controllers/post_actions_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe PostActionsController do
 

spec/controllers/posts_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 shared_examples 'finding and showing post' do
   let(:user) { log_in }

spec/controllers/queued_posts_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 require_dependency 'queued_posts_controller'
 require_dependency 'queued_post'
 

spec/controllers/robots_txt_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe RobotsTxtController do
 

spec/controllers/search_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe SearchController do
 

spec/controllers/session_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe SessionController do
 

spec/controllers/similar_topics_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe SimilarTopicsController do
   context 'similar_to' do

spec/controllers/site_customizations_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe SiteCustomizationsController do
 

spec/controllers/static_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe StaticController do
 

spec/controllers/stylesheets_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe StylesheetsController do
 

spec/controllers/topics_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 def topics_controller_show_gen_perm_tests(expected, ctx)
   expected.each do |sym, status|

spec/controllers/uploads_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe UploadsController do
 

spec/controllers/user_actions_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 require_dependency 'post_enqueuer'
 
 describe UserActionsController do

spec/controllers/user_avatars_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe UserAvatarsController do
 

spec/controllers/user_badges_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe UserBadgesController do
   let(:user) { Fabricate(:user) }

spec/controllers/users_controller_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'rails_helper'
 
 describe UsersController do