DATAREST-333 - Added controller mappings for OPTIONS requests.

The root resource, collection and item resources as well as the search and query method resources now expose a handler method to handle OPTIONS requests and return a response with the Allow header set to the HTTP methods appropriate to the resource requested.

Added some additional methods for HEAD requests and a few integration tests for functionality that previously existed.

Related ticket: DATAREST-330.
DATAREST-331 - Fixed NullPointerException in ResourcesProcessorWrapper.

During type matching in ResourcesProcessorWrapper we now accomodate the scenario that a Resources type is completely different than the Resources type to look for. This resulted in null being returned for the supertype generics lookup and this failed as the corresponding guard was missing.