Use Backbone for student account and profile JS.

Validate student account and profile form fields. Use RequireJS for Jasmine tests of account and profile JS.

@wedaly and @dianakhuang, could you review this?
In the interest of getting this merged in, I'm inclined to leave this as it is for now. These views will be revisited as we continue to work on the new profile and account pages, and we could decide to make the switch to a class-based view then. @wedaly, what's your take on this?