Add OHAttributedStringAdditions locally using CocoaPods in Example

OHAttributedStringAdditions is mainly meant to be imported using CocoaPods, so the Example projects now follows this by using a local Pod.
This seems strange (and wrong) as `OHAttributedStringAdditions` won't work on iOS6 (conflict with `NSFont` attribute type between `CTFontRef`/`UIFont` leading to crashes on iOS6 that were resolved by iOS7 and support of NSAttributedString by UIKit/TextKit) and needs iOS 7+.

So the demo project should also be iOS7+ and not iOS6 to avoid crashes too as well as inconsistencies with the Podfile.