Django 1.6 transaction incompatibilities

Django 1.6 handles transactions slightly differently to improve performance
and explicitness, however, the change has caused some backwards
incompatibilities documented here:
https://docs.djangoproject.com/en/dev/topics/db/transactions/#transactions-upgrading-from-1-5.

The ItemTestCase now needs to extend TransactionTestCase in order for it to run
without errors.