More tests, for items and Kit. This is showing up a couple of things:
(a) There's a "print" somewhere that's getting executed during the tests.
(b) Deleting an item that has a KitRequest does not also delete the corresponding KitRequest. So streampunk.tests.test_delete_items_with_stuff.test_items_kit is failing.
Added a delete() method to Item, so that it can clean up KitRequests, which otherwise hang around.

Also commented out all the print statements from the kit-satisfaction processing.
Having fixed the kit-request deletion in the model, I also need to fix the bug in the test, where I was checking for the wrong quantity of requests.
Added tag-deletion tests.