Allow service to be stopped while in 1s "starting" state

[benhoyt]

Per #408, if you try to stop a service while it's in the 1-second "starting" status, it will fail with the error "cannot start service while starting". We should probably make the service manager a bit cleverer in this case and allow the stop to succeed -- the fact that it's just been started shouldn't mean you can't stop it.

[benhoyt]

This is somewhat related to #240