Update setup_required to do the correct check for docker-in-docker

[danwinship]

The docker-in-docker supervisord setup uses different config files than the systemd setup, but we were deciding whether setup was needed based on whether the systemd files were correct.

@marun

[dcbw]

LGTM though do systemd managed and supervisord-managed really use different quoting in the docker options file? stupid if so but there's nothing we can do about it.