[appserver-io-dist/debian] Post-install fails for upgrade if one service is not running

[wick-ed]

If an appserver upgrade takes place the postinstall script checks for the status of the appserver processes and restarts them if needed.
If one of the processes is indeed NOT running (was observed with appserver-php5-fpm), the postinstall script will fail with status 3.

See the line of postinstall:
https://github.com/appserver-io-dist/debian/blob/master/src/8/dist/DEBIAN/postinst#L59

Assumption:
The exit code of the systemctl status command gets returned for the whole postinstall script