Updated lib to use ARC, created a podspec

Hey guys,

noticed your lib doesn't have a cocoapod. Now it does.

Along the way, I've updated it to use ARC and removed the outdated version of SBJson library (newer version is now a dependency - if you install your lib as a cocoapod it will just work)

Don't forget to request your podspec to be added here: https://github.com/CocoaPods/Specs


-Sergey