Cleaned up @rodchile's excellent work integration OAuth 1.0 and 2.0 into RestKit. Changes
are as follows:
* Introduced new RKRequestAuthenticationType to replace the forceBasicAuthentication and other
methods for influencing how authorization works.
* Moved TDOAuth code into Vendor/
* Renamed authorization code flow classes and delegate methods for clarity.
Other changes include:
* Eliminated the RKObjectFactory protocol and implementations. Object mapping instances themselves are
now responsible for instantiating target objects for mapping.
* Introduced RKObjectAbstractMapping superclass for RKObjectMapping and RKObjectPolymorphicMapping.
* Updated example applications to use block object loaders (RKTwitter and RKTwitterCoreData)
* Refactored method signatures of RKObjectMapper, RKObjectMapping, and RKObjectMappingProvider to reflect the
existence of abstract mapping types. This was necessary to make polymorphic mappings integrate cleanly.
* Fixed overlap in RestKit error domains between network and object mapping. fixes#208
* 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
