Implementation of the OnCardSwiped-Listener, slight change for more backwards-compability

I implemented the OnCardSwiped() - Listener by calling it inside onDismiss() in CardStack. Furthermore, I changed the Example to use the library color R.color.stroke instead of holo_blue_light for more backwardscompability.

Sorry that the Eclipse-Autoformatting kinda "destroyed" the nice way to see the changes.

I can try to reproduce without autoformatting, if you don't accept it otherwise.