Port zoom-in and zoom-out functionality from animate.css

Adds the following from animate.css:

[https://github.com/daneden/animate.css/tree/master/source/zooming_entrances](https://github.com/daneden/animate.css/tree/master/source/zooming_entrances)
[https://github.com/daneden/animate.css/tree/master/source/zooming_exits](https://github.com/daneden/animate.css/tree/master/source/zooming_exits)