much better webapp startup of the assistant

This avoids forking another process, avoids polling, fixes a race,
and avoids a rare forkProcess thread hang that I saw once time
when starting the webapp.

Command/Watch.hs

@@ -34,5 +34,5 @@ start :: Bool -> Bool -> Bool -> CommandStart
 start assistant foreground stopdaemon = notBareRepo $ do
 	if stopdaemon
 		then stopDaemon
-		else startDaemon assistant foreground -- does not return
+		else startDaemon assistant foreground Nothing -- does not return
 	stop