Always include AttemptLogs with context_type either playlist or exercise.
Upgrade django-south from 0.7.6 to 0.8.4 (to support index_together)
Add index_together on AttemptLogs to make typical queries much faster.
Middleware to allow tastypie requests to be profiled with debug toolbar.
Merge pull request #2802 from jamalex/include_all_practice_attempts

Improved AttemptLog filter (for efficiency and correctness)