Organization and Zone deletion tests and bugfixes

This is dependent on #697

We are shipping a potentially dangerous feature (deleting empty zones and organizations), but have no tests to check the basic scenarios.

I implemented those tests and, while doing so, found two bugs:
* Deleting an organization failed when a facility (on an unrelated org/zone) exists.
* Misspelling successful as succesful in all success messages.

I've also implemented some test-only changes, to accommodate the new tests.  New tests range from:
* Deleting org/zone
* Clicking cancel in dialog (making sure no delete)
* No links appear when org/zone not empty.

@dylanjbarth this is all you.