db_manager: postgres:// -> postgresql://

The old scheme is deprecated.
Make it possible to run all automated tests via `nosetests`.

This setup assumes the existence of a `test.ini` file. No current tests
mutate backend state, but that may happen in the future so don't make
your test.ini point at production!
setup.py: Remove unused and potentially confusing commands.
setup.cfg: Remove cruft.
tests: Fix up tests for r2.lib.tracking.