Allow TAs to impersonate Students that are participating in the same class that
the TA is assisting in.
Always return an array from `AssignmentParticipant#get_participants`
even if it is an empty array
Increase the sessions store to 4MB
The first name of a User with a fullname format of 'last, first mi' or 'first
last' retrieves the correct first name.
Fix Issue #372 - method called on nil in MenuItemsController