Trying to stop a service that isn't running is not an error

Now when you try to stop a service that is not running, it exits cleanly rather than issuing an error code. The intent "service should not be running" is satisfied even though we didn't actually have to stop it.

This allows init.d scripts to do things like "shut down naught" just by saying "naught stop". If naught was not already running, we really don't care. It should be stopped, that is the point.

Modified the unit test to expect exit(0) status in this case.