CLC-2173 Start at Canvas embedded official roster viewer

https://jira.media.berkeley.edu/jira/browse/CLC-2173

Server-side mostly in place. Client-side just barely counts as proof that the code more-or-less works.

To dos:

1. Finish the client-side embedded view, of course.
2. Full instructions on adding the app to a Canvas instance.
3. Lots of checks on caching, etc.
4. Add CalCentral-hosted view of the roster to make development easier. (Same inner view/controller; different layout container.)
5. Global JavaScript change to fix iframe size for embedded app?