This takes care of a few different breakages in the test suite when
running on more modern versions of Django. These have to do with a
couple of individual unit tests, rather than implementation issues in
Djblets.

It also fixes up the Djblets test suite runner to use the migrate
command instead of syncdb when populating the database before the test
runs.

Along with all the other changes going up, the unit tests pass on

Django 1.6 through 1.10.