Merge branch 'followed-attribute' into 'master'

added 'followed' to user_serializer

See merge request !369

app/serializers/user_serializer.rb

 class UserSerializer < ActiveModel::Serializer
-  cache key: 'user', expires_in: 4.hours, except: [ :complained ]
+  cache key: 'user', expires_in: 4.hours, except: [ :complained, :followed ]
 
   def complained
     object.complained? current_user
   end
 
-  attributes :id, :email, :provider, :name, :description, :role_ids, :institution_ids, :avatar, :likes_count, :complained, :follows_count, :learning_objects_count, :collections_count, :created_at, :updated_at
+  def followed
+    object.followed? current_user
+  end
+
+  attributes :id, :email, :provider, :name, :description, :role_ids, :institution_ids, :avatar, :likes_count, :followed, :complained, :follows_count, :learning_objects_count, :collections_count, :created_at, :updated_at
 end