don't fork when run from systemd #972

Unit file for systemd. Systemd, contrary to System V Init, is not a set of scripts and processes don't need to daemonize themselves because they are already daemonized by systemd. systemd runs the process from parent PID 1, stdout/stderr are redirected to systemd-journald, and the process doesn't own tty. For these reasons, Archipel doesn't need to daemonize itself because it's already daemonized by systemd. Just like php-fpm doesn't, and lots of other applications don't. https://bugs.php.net/patch-display.php?bug=63085&patch=php-fpm-systemd.patch&revision=1348066817