* Removed RestKit from inheritance hierarchy
* Mappings are implemented as concrete classes
* Mapper is much more flexible & powerful
* Much more robust error handling
* Serialization is reimplemented as an object mapping operation
* Added ability to serialize to JSON natively
* Reworked Core Data integration
* Simplified the codebase substantially
* Cleaned up various mismatches in method signatures that were preventing documentation generation
* Removed naked ampersands from comments as they cause XML parser failures during docset generation via appledoc
* Introduce RKObjectMappable#relationshipsToSerialize to define nested relationships to post
* New helper methods for working with relationship serializations.
* Extended Rails router to serialize nested objects according to Rails idioms