isCollection() method returning true for entities

As noted on the [mailing list](https://groups.google.com/a/zend.com/d/msgid/apigility-users/c4cfcb3e-6e99-4ee1-9968-080f8abb5096%40zend.com), the logic for determining whether to validate an incoming request as a collection or as an entity is currently broken.

The error appears to be on line 306; when the identifier is found in the route matches, we should be returning `false`.