2.4.1
Bumping copyright year
[Issue #2187][Issue #2245][Issue #2255] Adding image cache and response serializer properties to UIButton category, as well as cancelling image request operations correctly on a per-state basis
Resolve compiler warning about "Values of type 'NSUInteger' should not be used as format arguments; add an explicit cast to 'unsigned long' instead"
AFImageCache protocol should inherit from NSObject
Import UIRefreshControl+AFNetworking
Adding explicit casts and #pragma ignore to fix warnings about out-of-range enumerated type value assignment
Adding UIRefreshControl+AFNetworking