Fix configforms tests on Django 1.8+

Review Request #7919 — Created Jan. 29, 2016 and submitted — Latest diff uploaded

Information

Djblets
release-0.10.x
282b771...

Reviewers

The setUpClass method was missing a super() call and so the class wasn't
being properly instantiated, leading to errors when it was being torn
down. This patch fixes that.

Ran unit tests on Django 1.6 and 1.8; they passed in both cases.