Use case: Queue is used to sign off students. Student signs up
with a "submission" request type, and is handled by a TA. Last
request of every assignment is selected and its status is logged in
a CSV dump.
Things to note:
The value for a student-assignment combination can by any value
in the Requests.Status enum, or the special "NO_REQUEST" value if
there has never been a request in the queue for this student for this
assignment.
Dump only lists the status of the last request, so if a student is
accepted but later signs up again, the accepted status is dropped in
favor of the new status
If the latest request is changed after the fact, the dump will show
the latest, updated status.
Users who never signed in to the queue in the first place will not be
part of the dump, so if these exist in BS, rules should be set properly
for them to get a failing grade.
