Remove AFNetworking from demo

I don't really want to pull AFNetworking into a project's repo for no reason, so, I made a quick lil wrapper for NSURLConnection with associated objects in PDViewController.

I can understand the need for a sample for a popular framework out there, but, really, it seems like overkill for something that A. Just Works, without any other changes needing to be made to the networking code and B. doesn't do anything complicated with HTTP (the demo, that is).