Remove unused submission ID from perf tests
Update perf test to load steps in parallel.
Update perf test to hit end-points whether they're ready or not
Generalize problem fixtures, select rubric options at random
Add continued assessment to peer step
Add example-based grading to perf test
Update test course and readme
Update ddt to 0.8.0
Clean up logging in peer and self assessment mixins
Catch a peer API workflow exception
Update the Vagrant configuration to use:
* gunicorn
* nginx
* mysql
* memcached
* celery flower
* upstart

Set file encoding for Python interpreter to fix a test failure in the Vagrant VM.
Configure Vagrant log files to go to logs/vagrant.
Serve workbench URLs from /
Use UTF-8 encoding the MySQL database
Add more gunicorn workers
Include setting the classifier set in the transaction that creates AIGradingWorkflow
Added the appropriate server call to the JS.
Update test course to include example-based assessment for all supported configurations
Train classifiers in the simulate_ai_grading_error management command
Remove cache key versioning
Unified exception handling and logging policies
Expanded logic of how classifiers are assigned to AIGradingWorkflows.
Added a course_id field and item_id field to AIClassiferSet, to allow quick
queries.  Updated test cases to refelect these changes