1. Rename db attribute 'team_count' to 'max_team_size' in table 'assignments'.
2. Rename 'num_of_choosers' to 'available_slots'
3. Rename 'waitlisted_choosers' to 'num_waiting'
Removes is_waitlisted from the validates statement.
For some reason, the code did not work with
is_waitlisted in the statement, regardless of whether
it is initialized to 'true' or 'false'.  Either way,
SignedUpUser had not been able to be saved.
Refactor signup sheet views for instructor and student to use common codes to display signup topics.
Merge branch 'master' of https://github.com/expertiza/expertiza