Correct oral presentation forms not being accepted

The guard for the accepted state of the oral presentation forms was
comparing a set of accepted users to the array of all users. This
comparison always returns false. We now compare two sets in order
to correctly determine equivalence.
Mark accepted oral presentation forms as completed

Oral presentation forms were not marked as completed when they were
accepted. This caused them to linger in the pending tasks list after
they had actually been completed.