Make monitor script a daemon

[abh]

Change monitor script to run continuously (under supervise, systemd, launchd etc – not daemonized, though that could be an option, too).

Whenever the last API 'poll' returned servers to check it should do so again immediately after posting results; if there were no servers to check, wait two minutes before polling again.

[loewis]

I propose https://github.com/loewis/ntppool/tree/issue12 as a patch. This creates a systemd "simple" service, which terminates on SIGTERM. I left in all the dies, which I hope should show up in the log files somehow. In some of the cases, it is probably better just to log an error message, and continue with the next loop iteration. If it dies, it should be the responsibility of the process manager to restart it (taking into consideration restart frequencies and such).

[abh]

Didn't test it, but at a glance it looks good. Thanks! I pulled it into my master branch and will try it later.

[abh]

commit 4e87625
Author: Martin v. Loewis martin@v.loewis.de
Date: Sat Jun 4 22:38:49 2011 +0800

Change monitor script to loop until SIGTERM is received,
or an error occurs.