Updated to AFNetworking 2.0 for support of NSURLSession
Merge pull request #8 from mmorey/AFNetworking2

Updated to AFNetworking 2.0 for support of NSURLSession
v0.1 drops support for iOS 5/6, AFNetworking 2.0 required now
Specifying v2.0.1 of AFNetworking since v2.0 has issues