Signup form: prefill username if Discourse Hub has a match for the email address. Also, fix some bad specs in username_checker_service_spec that were passing...

lib/discourse_hub.rb

@@ -32,6 +32,11 @@ module DiscourseHub
     [json['match'], json['available'] || false, json['suggestion']]
   end
 
+  def self.nickname_for_email(email)
+    json = get('/users/nickname_match', {email: email})
+    json['suggestion']
+  end
+
   def self.register_nickname(nickname, email)
     json = post('/users', {nickname: nickname, email: email})
     if json.has_key?('success')
@@ -100,7 +105,7 @@ module DiscourseHub
     if Rails.env == 'production'
       'http://api.discourse.org/api'
     else
-      'http://local.hub:3000/api'
+      ENV['HUB_BASE_URL'] || 'http://local.hub:3000/api'
     end
   end