- namespace & document test accounts in README.md
- standardize the password format everywhere, and ensure the passwords
differ everywhere.
- Add MITOGEN_TEST_DISTRO environment variable.
e.g. assert x == y -> self.assertEqual(x, y);
self.assertTrue(isinstance(x, y)) -> self.assertIsInstance(x, y)
These specific methods give more useful errors in the case of a test
failure.