Added a test case for TaskManager. Mocked out scheduling of Celery task for archiving tasks in applicable tests and added tests to verify the effects of archival. Added comments for all test case methods.
Stopped skipping archival task for eager requests. Added a necessary break that was missing in the watch for the set of done tasks (or else the job will loop infinitely).
Set a task to current (if not already set) when marking it done.