fixes #4892 - content view filters & rules api - return object on DELETE

When a content view filter or rule is deleted with the API, return
the object that is being deleted.

This is correct behavior according to the API documentation and
is assumed behavior for the UI to properly update lists during
a deletion.
Merge pull request #3897 from bbuckingham/issue-4892

fixes #4892 - content view filters & rules api - return object on DELETE