Merge branch 'patch-58' into 'master'

delete feature flag when disabling Rugged

See merge request gitlab-org/gitlab-ce!28289

lib/tasks/gitlab/features.rake

@@ -17,7 +17,7 @@ namespace :gitlab do
       if status
         Feature.enable(flag)
       else
-        Feature.disable(flag)
+        Feature.get(flag).remove
       end
     end
   end