KA test framework changes

This looks like a big pull request, but it's just messy.  It's all test code, and I suggest just a cursory review, to make sure these tools will be available for tomorrow's training.

**Background:**
This pull request merges code that has been far ahead of develop, back into develop, by removing future dependencies.

**Changes**:
* Add "playground" code as a sub-repo.  Some of the "playground" code is used in the "ecosystem" test cases (which have been removed here, but I hope to have ready, in a secondary form, through a second pull request tomorrow morning, for tomorrow)
* Break utils/testing.py into 3 major parts (utils/testing/*, and move central and main code into their respective testing files)
* Implement smarter form entry systems, to allow more robust keyboard-based navigation in testing.

**Testing**:
* I ran the test suite on both central and main servers (`./manage.py test` on each).