ids-functions.pl: Add function to get the version of suricata

ids-functions.pl: Add function to get the version of suricata

The get_suricata_version() function is used to get the version
of the on the system installed version of suricata. You can
specify the how detailed the returned result should be "major" will
return only the major version, were "minor" will provide the major
and minor version (1.2 for example). All other calls will be answered
with the full version string (1.2.3).

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