Changes to the daf_persistence tests so that they all use unittest and they all skip properly if the db-auth.paf file is missing.

Interesting oddity is that some tests fail if launched in one invocation of py.test if DbAuth.py is the first in the list of tests.

I have fixed the DbAuth.py problem. It was caused by the policy from that test not being reset and so affecting the later tests.

looks fine. I didn't see a pull request so I created one, mostly to make it easy to diff (that's the right thing to do?). That gets closed automatically when you merge?

Thanks. Creating a PR is fine. I tend to leave it to the reviewer as sometimes people don't feel like making any comments.

PR merged.