API: restore broken merge request commenting

lib/api/entities.rb

@@ -75,5 +75,10 @@ module Gitlab
       expose :author, using: Entities::UserBasic
       expose :updated_at, :created_at
     end
+
+    class MRNote < Grape::Entity
+      expose :note
+      expose :author, using: Entities::UserBasic
+    end
   end
 end

lib/api/merge_requests.rb

@@ -107,7 +107,7 @@ module Gitlab
         note.author = current_user
 
         if note.save
-          present note, with: Entities::Note
+          present note, with: Entities::MRNote
         else
           not_found!
         end