better webapp startup, using the terminal app's default command config

This allows the user to turn it off easily, or only start the assistant and
not the webapp.

I was not able to determine why having runshell run the webapp segfaulted.
Strace was not helpful. Oh well, this is better anyway.

standalone/android/runshell

@@ -113,9 +113,6 @@ run () {
 		# As good a start point as any.
 		cd "$HOME"
 
-		$cmd echo "Starting git-annex interface, please wait ..."
-		$cmd nohup git-annex webapp || $cmd true
-		$cmd echo "The git-annex interface is no longer running."
 		/system/bin/sh
 	fi
 }