* 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 remaining warnings about if (self = [super init])
* RKParamsExample - Highlights multi-part uploads
* RKRequestQueueExample - Working with the request queue
* RKBackgroundRequestExample - Examples of using the background policies for backgrounding requests
* RKReachabilityExample - Shows how to work with the reachability observer
* RKRelationshipMappingExample - Shows how to map related objects from JSON into an object graph
* RKCoreDataExample - Shows the basics of using RestKit's Core Data examples
Also rearranged dispatch of RKRequest delegate method for didStartLoad: to ensure requeue callbacks get invoked in a timely manner. refs #62
* 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
