Revert "added OCMAdditions category to NSProxy"

This reverts commit 1bb77abe5f1da82d40a88ca5a111b86888ea5f27.
removed partial mocking of mock in description test

OCMock doesn't seem to handle mocking of proxy objects well.  I think this can fairly be considered a rare (and dubiously useful) case.  As such, I'm content with the test passing without verification that the __isNS* methods are being called.
changed isNS*__ method handling

partial mock would go into infinite loop when checking `isSubclass` instead of `kindOfClass`