Merge branch 'backbone' of https://github.com/jamalex/ka-lite into backbone
Fix student_testing.
Implement start and stop screens for tests.
Merge branch 'backbone' of https://github.com/jamalex/ka-lite into backbone

Conflicts:
	kalite/student_testing/models.py
Add context_type filtering to AttemptLog Resource.
Filter AttemptLogCollection fetching by context_type.
Fix sequencing of tests.
TODO: Get start of test to work without reload.
Make answer question button identical on incorrect or correct answer in test mode.
Merge branch 'backbone' of https://github.com/rtibbles/ka-lite into backbone

Conflicts:
	kalite/distributed/static/js/distributed/exercises.js
	kalite/distributed/templates/distributed/exercise.html