Update AFIncrementalStore for AFNetworking 2.0.0-RC2 support

The following issues have been resolved:

* Compiler issues related to 'OS_OBJECT_USE_OBJC' flag defaulting to 0 in SDK targets below iOS 6.0. 
* Depreciated uses of AFHTTPClient method 'requestWithMethod:path:parameters:' migrated to 'requestWithMethod:URLString:parameters'
* All example targets updated to work with AFNetworking 2.0.0-RC2