Optionally manage a daemon during selftest runs

If a mudpy config file is supplied when invoking the selftest suite,
use it to start the service. This is intended for use with testing
automation such as tox. Handle both daemonized/disassociated and
direct child process possibilities, and attempt to clean the up
afterward. Also clean up the test environment when starting in case
stale processes or old logs were left behind by a previous run.