ids.cgi: Stop suricata when the rulest source has been changed

If the ruleset source has been changed, it has to be configured again.
This happens because of different rule categories, filenames rule ID's etc.

In case suricata currently is running it has to be stopped and after the configuration
has been done by the user, it can be launched again.

Signed-off-by: Stefan Schantl <stefan.schantl@ipfire.org>