ORA tests and fabfile refactor

* Added ora self-assessment test
* Added basic test for AI assessment
* Refactor fab file commands

I had to refactor the fab file to create a new command to run the ORA tests.  Along the way I made a few other changes:

1) Replaced "cms" with "studio" throughout.  I'd like to move away from the cms naming convention, which I suspect is confusing to open-source contributors.

2) Renamed `test_lms` to `test_edxapp_lms` to emphasize that `lms` is contained in `edxapp`.  Likewise for Studio and ORA.

3) Refactored the "test spec" logic.

One of the ORA tests is still failing in my sandbox (created this morning) -- it's the same error that I thought Cale had fixed, but I guess hadn't merged into master yet.

@jzoldak