Backbone version of the course outline page

STUD-1726

First cut at backbonified outline view
I found this on a Stack Overflow article describing how you can dispatch to different services for read vs write. In my case, I need to have reads go to '/xblock/outline', but I still need writes to go to '/xblock'. Overriding the method like this causes save and fetch to correctly use the right methods.

http://stackoverflow.com/questions/7644767/backbone-js-use-different-urls-for-model-save-and-fetch

I'll add comments.