FEATURE: Configure Admin Account

Adds a "Step 0" to the wizard if the site has no admin accounts where
the user is prompted to finish setting up their admin account from the
list of acceptable email addresses.

Once confirmed, the wizard begins.

app/controllers/finish_installation_controller.rb

@@ -0,0 +1,53 @@
+class FinishInstallationController < ApplicationController
+  skip_before_filter :check_xhr, :preload_json, :redirect_to_login_if_required
+  layout 'finish_installation'
+
+  before_filter :ensure_no_admins, except: ['confirm_email']
+
+  def index
+  end
+
+  def register
+    @allowed_emails = find_allowed_emails
+
+    @user = User.new
+    if request.post?
+      email = params[:email].strip
+      raise Discourse::InvalidParameters.new unless @allowed_emails.include?(email)
+
+      return redirect_confirm(email) if User.where(email: email).exists?
+
+      @user.email = email
+      @user.username = params[:username]
+      @user.password = params[:password]
+      @user.password_required!
+
+      if @user.save
+        @email_token = @user.email_tokens.unconfirmed.active.first
+        Jobs.enqueue(:critical_user_email, type: :signup, user_id: @user.id, email_token: @email_token.token)
+        return redirect_confirm(@user.email)
+      end
+
+    end
+  end
+
+  def confirm_email
+    @email = session[:registered_email]
+  end
+
+  protected
+
+    def redirect_confirm(email)
+      session[:registered_email] = email
+      redirect_to(finish_installation_confirm_email_path)
+    end
+
+    def find_allowed_emails
+      return [] unless GlobalSetting.respond_to?(:developer_emails) && GlobalSetting.developer_emails.present?
+      GlobalSetting.developer_emails.split(",").map(&:strip)
+    end
+
+    def ensure_no_admins
+      raise Discourse::InvalidAccess.new unless SiteSetting.has_login_hint?
+    end
+end