Makes new tables that are queryable to get aggregate data on student per
problem information and student grades at three levels: overall course,
assignment type, and assignment.
Provides UI in instructor dashboard to view student metrics using
class_dashboard app.
Remove primary keys from queryable tables
De-normalize user info of id, username and name into queryable tables.
Make all tests pass
* use default parameter in get_or_create for non-unique-together
values
* properly set module_state_key
Conflicts:
lms/envs/test.py
