API: fixed adding a note

Now the correct attribute is checked if it's available or not. Also fixed a test.

lib/api/notes.rb

@@ -93,7 +93,7 @@ module Gitlab
         #   POST /projects/:id/issues/:noteable_id/notes
         #   POST /projects/:id/snippets/:noteable_id/notes
         post ":id/#{noteables_str}/:#{noteable_id_str}/notes" do
-          required_attributes! [:"#{noteable_id_str}"]
+          required_attributes! [:body]
           @noteable = user_project.send(:"#{noteables_str}").find(params[:"#{noteable_id_str}"])
           @note = @noteable.notes.new(note: params[:body])

spec/requests/api/projects_spec.rb

@@ -466,8 +466,7 @@ describe Gitlab::API do
         response.status.should == 200
         json_response.should be_an Array
-        #json_response.first['id'].should == project.repository.commit.id
-        json_response.size.should == 1
+        json_response.first['id'].should == project.repository.commit.id
       end
     end