After animation event support on a per view basis

Just to preface, I'm quite to Backbone and js in general so feedback is very much appreciated :-).

I added very basic support event triggering on a per-view basis. Currently, I was only concerned with triggering events on animation complete. My changes end up providing a very similar syntax to Jr.Navigator.navigate. In the Junior view initialization, I would type something similar to:
```javascript
Jr.Navigator.addEventListener("animationComplete", "viewURL", callback, context);
```