Made a PSMTabBarControl cocoapod that uses ARC

- This works on 10.9 (Mavericks) with Xcode 5.0.2
- I have not checked if it works on older OS X versions
- I have not checked if it compiles with older Xcode versions

The biggest change is to the xcodeproj file. I had to change all files references to a file structure that works well with cocoapods.