Stop statically compiling AFNetworking in

[joeldev]

I was lazy and it made it easy to deliver a single release binary that was 100% good to go, but people seem opposed to it. Oh well

[joeldev]

This is done for iOS, and there are now two variants of the build in Release. libADNKit-iOS.a does NOT include AFNetworking by default, and libADNKit-AFNetworking-iOS.a DOES include it by default.

[tonyarnold]

Once #53 is in, I'd love to take a swing at this for OS X, and update to use AFNetworking 2.x (or NSURLSession and friends if it's more appropriate).