ZyXel GS1910 Ethernet Switch support

The GS1910-24 (and friends) are not properly detected as being ZyXel.

The sysdescr in SNMP seen by Observium is:
"GS1910-24 24x1G Ethernet Switch"

Also there is a "XGS1910/GS1910" in 24/48 port configuration. Hence a new entry of:

Adding /opt/observium/includes/discovery/os/zyxelgs.inc.php

<?php
if (!$os)
{
if (!$os)
{
if (preg_match("/^[X]?GS1910 (24|48)x1G Ethernet Switch/", $sysDescr))

Unknown macro: { $os = "zyxeles"; }

}}
?>

detects this properly.