Use framework modules
Use NS_ENUM macro for enumerated types
Update .gitignore
Lots of cleanup and refactoring!

* Added bdb_ prefix to all category methods and properties
* Reformatted for easier reading, added braces to all conditionals for added safety
* Use CAKeyframeAnimation for BDBPopupViewShowAnimationZoomIn instead of nested UIView animate: calls
* Added animation completion callback to CAKeyframeAnimation using internal delegate class
Remove AHEasing submodule
Update demo project