1120671 - missing operation from reaper and monthly tasks

I also added documentation about these tasks
I don't think this should require *args, **kwargs. The apply_async on the Pulp Task class should strip off Pulp specific arguments (tags=tags), and any other arguments will be stripped off by celery's apply_async up the call chain. I bet if you remove these it will work perfectly. I think this method should take no arguments.