Also fixed:
* The if statement near line 674 was incorrectly negated
* Setting the relationship value around line 676 was redundant since it was done in the mapCoreDataToManyRelationshipValue:withMapping method.
* Metadata mapping is implemented via an `NSProxy` object that stands in for the `sourceObject` of each `RKMappingOperation`
* Key paths that are prefixed with `@metadata.` are mapped against the `metadata` dictionary of the operation, else they hit the `sourceObject`.
* Metadata is implemented by merging a dictionary of data in from `RKObjectRequestOperation`, through to `RKResponseMapperOperation`, into `RKMapperOperation`, and all the way down into the `RKMappingOperation`, where it is available to each object. By convention, metdata is namespaced into subdictionaries.
1. Eliminates use of visitor in favor of aggregating mapping info during mapping. This avoids having to traverse the mapping graph.
1. Eliminate special case handling of cyclic key paths.
1. Eliminate issues with infinite recursion while traversing the mapping graph.
* Rename RKDynamicMappingMatcher to RKObjectMappingMatcher since it is not strictly coupled to dynamic mapping and works with object mappings.
* Rework matchers into using a class cluster style to enable flexible subclassing to introduce additional matchers.
* Change contract to the use the `description` method instead of `errorMessage`. This makes it work with any class out of the box
* Add import for RKErrorMessage to the Support.h header so it is immediately available
* Fix incorrect keyPath in the README.md
* Add additional notes about how the errors are constructed to the README
* Inversing non intelligently walks the mapping graph, ensuring that cyclic graphs are resolved properly
* Copy all attributes from the parent to the inverse mapping (date formatters, etc)
* Replaces primary key with `RKEntityIdentifier`
* Add support for use of compound keys for object identification
* Refactor `RKConnectionMapping` to `RKConnectionDescription` and add support for connecting with multiple attributes
* Clarify naming of representation key methods to better match naming conventions
* Add type transformation support for object identification
* Greatly expand test coverage for object identification
* Drop the `NSEntityDescription` category
* Simplify the `RKManagedObjectCaching` protocol
* Add compound key support to the Fetch Request and In Memory Cache implementations
* Replace Kiwi with Specta for tests where contexts are helpful for organization
* Rename `defaultValueForMissingAttribute` to `defaultValueForAttribute`
* Renamed RKObjectPaginator to RKPaginator for simplicity
* Removed delegate on paginator in favor of simple success/failure blocks
* Added `willMapDeserializedResponseBlock` for manipulating the response body before mapping begins
* Added support for cancelling an in-progress pagination request
