Cleanup user creation in tests

Review Request #9458 — Created Dec. 19, 2017 and submitted — Latest diff uploaded

Information

Review Board
release-3.0.x
879fdfd...

Reviewers

We now are always careful to provide an e-mail to users in tests. Also,
calls have been updated to use User.objects.create_user over
User.objects.create where appropriate. This was prompted by a change
in Djblets (see https://reviews.reviewboard.org/r/9445/) which started
causing unit test failures due to Users without e-mail addresses
being serialized. So to be extra safe, I've gone in and added e-mail
addresses to all calls that were lacking them.

Ran unit tests.