api-search-googletranslate: Improved API error handling

* Exceptions thrown while processing an API request now return the
  proper JSON formatted error response without the need for custom
  handling. If `DEBUG=True`, this behavior is disabled and Django
  will return the full traceback.
* Added support for custom status code (and any argument for
  HttpResponse) to `APIView.render_to_response`
* Added check for status code to `api_check()`

Note - the changes are backward-incompatible.