fixes #7756 - render not_found.json.rabl for API errors rather than expose too much internal information

There wasn't really a reason to override ```:class```, ```:message``` however, sends the user very informative messages like ```Couldn't find all Domains with IDs (1, 2) (found 0 results, but was looking for 2)```. 
I thought it was good, but if that's dangerous information then let's get rid of it.