Zabbix

.......PS. [ZBX-12708] fixed port validation during autodiscovery

If the auto-discovery is performed using a zabbix proxy, a condition
for the validation of the reported service port will always be set to
0 if the validation is successful.
Split the check in two (first check for tags, after validate the port value)
and set the port to 0 only if a tag is not present.

Discussed with Vladislavs Sokurenko

[svn merge ^/branches/dev/ZBX-12708]