The review request draft resource passed in any review request IDs to

the queryset when attempting to get a list of valid and invalid IDs.

However, if one of the values passed in was not an integer, this would

trigger an error within Django, which would crash the API request.
The resource now pre-filters the values, querying only the ones that

resolve to integers. Anything else ends up in the list of invalid IDs

that are reported to the client.

Unit tests pass.