Updated CourseAssignment __unicode__
Also returns user's full names now.
PEP8 styling fixes
Updated CourseAssignment's __unicode__.
Previous commit was false and didn't do it.
Removed fields from Task's unique_together
Unneeded explicity. A task is unique if it has a unique name and description.
No need to check uniqueness including fields - is_exam, course and week.
Added extra info how to use Django with MongoDB