feat(Learning Objects: add 'has_liked' field

app/serializers/learning_object_serializer.rb

@@ -19,7 +19,28 @@ class LearningObjectSerializer < ActiveModel::Serializer
     object.object_type.try(:name)
   end
 
-  attributes :id, :name, :description, :author, :thumbnail, :publisher, :object_type, :language, :default_attachment_id, :default_location, :default_mime_type, :score, :license, :likes_count, :shares_count, :created_at, :updated_at
+  def has_liked
+    object.liked? current_user
+  end
+
+  attributes :id,
+             :name,
+             :description,
+             :author,
+             :thumbnail,
+             :publisher,
+             :object_type,
+             :language,
+             :default_attachment_id,
+             :default_location,
+             :default_mime_type,
+             :score,
+             :license,
+             :has_liked,
+             :likes_count,
+             :shares_count,
+             :created_at,
+             :updated_at
 
   has_many :tags
   has_many :attachments