Add gem for testing mailers
Initial db stuff for scheduled events.
Initial scheduled events. For now we can create them (in one place) and
they send out nag emails. So there's still a bit to do.
View scheduled events along with other file group events.
Added ability to cancel/complete scheduled events from event index table.
Add url for events view to nag email.
Fix things up so the test environment will continue to use the :test
mail delivery but still be able to generate urls in the mailer.