Backbone version of the course outline page

STUD-1726

Converted the course outline page to Backbone so as to support dynamic client-side updating.
I think there is an assumption about the structure either way. This test works with any of section/subsection/unit, section/split_test/subsection/unit and section/subsection/split_test/unit. If we add future split_test like classes in between it can accommodate them. The key is that the course outline shows everything down to units, and then units have their own dedicated pages.