The test runner was attempting to discover tests in the

django_evolution.tests.db.* package, which triggered database

connections and caused errors with testing if a particular database

wasn't configured or running.
We now use the nose-exclude plugin and a configuration option to tell

nose not to look for any tests there. This plugin is required due to

the fact that --exclude and -ignore-files won't work on directories.

Added some asserts to the test data files to simulate the behavior

being seen in CI. Saw the failures prior to the new option and plugin.

After, those modules weren't being imported and all tests passed.