Instead of relying on reference to the RKMapping, which could be dynamic, traverse from the attribute mapping back to its parent to obtain the appropraite date formatter.
* RKObjectParameterization now returns an empty dictionary if mapping produces an unmappable representation error (no mappable attributes/relationships found)
* Log errors if request construction results in an NSError and return nil
* Ensure errors are passed back up through object parameterization instead of just returning nil
* Reset the serialization MIME Type registry during RKTestFactory set up to ensure it is in a sane state
* Convert Hamcrest matchers to Expecta in the object mapper tests to fix infinite recursion on test failure (will need to completely phase out Hamcrest soon)
* Adds support for NSJSONSerialization. closes#476
* Renames RKParser to RKSerialization
* Renames RKParserRegistry to RKMIMETypeSerialization
* Rework serialization implementations API's to use class methods
* Fold together string and regular expression matching for MIME Type registrations
* Port serialization implementations to working off of NSData instead of NSString. refs #762
* Migrate JSONKit to being an optional component. See https://github.com/RestKit/RKJSONKitSerialization
