Refactor of AFNetworking & Pods integration

Hello

In this pull request I've refactored AFNetworking to being SLAFNetworking. This will solve any issues with those who are using AFNetworking 2.0. I think it's bad practice to force user's of this library to use an out of date AFNetworking. On another note about this, is the project being worked on to move it to AFNetworking 2.0? If not I plan on doing this as well in the upcoming week(s).

I've also added a podspec file for compatibility with cocoapods. I didn't add anyone for authors - figured I'd leave that up to someone at strongloop. For podspec syntax see the following: http://guides.cocoapods.org/syntax/podspec.html

I will also be making a corresponding pull request on loopback-ios that accounts for the changes in this pull request.