* Passes through cancellation from object request operation to HTTP request operation and response mapping operation. closes#993
* Performs all object mapping within an NSOperationQueue to enable constraining of mapping activities.
* Add default mapping queue with concurrency limit of 1 operation.
* Migrate deserialization of the response body into a serial dispatch queue to ensure that only one parse occurs at a time.
* Reworked execution of relationship connection operations to use dependencies instead of queue suspension.
* Migrates responsibility for connecting relationships from `RKManagedObjectRequestOperation` into `RKManagedObjectResponseMapperOperation`. This ensures that you get a mapped and connected object graph back from the response mapper if you are using it outside of a request operation.
* Add `parentOperation` to managed object mapping data source to establish dependencies.
Instead, fall back to treating all URL's as strings for matching purposes and manually performing relative URL testing. Adds `matchesURL:` and `matchesResponse:` methods to `RKResponseDescriptor`.
* 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
