The recent change to fix stale broker connections failed to actually

store the revised broker URL used to help indicate if a connection was

stale. This led to creating a brand-new Celery connection every time the

property was accessed, and broke unit tests in the process.
This change fixes that, and also improves test infrastructure by

supplying a default settings_local.py file that can be used. This

avoids needing to have one already set up in a dev server in order to

run tests.

Unit tests pass, without a settings_local.py being in the Python path.