* 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