FirewallObjects, FirewallRules: fixed translation labels. Refs #2705
FirewallRules/CreateHostGroup: enforce strict members key check. Refs #2705
FirewallObjects/Services: mark Ports field as NON-EMPTY. Refs #2705
FirewallObjects/Services: use Modify class for "delete" case. Refs #2705
FirewallObjects: run event as a detached task. Refs #2705
FirewallObjects: check if object exists on validate(). Refs #2705
FirewallObjects: check rules references integrity before delete. Refs #2835

* Added getReferences() to NethServer::Firewall perl module.
* Defined new system validators:
** fwobject-host-group-delete
** fwobject-host-delete
** fwobject-zone-delete
** fwobject-fwservice-delete
FirewallObjects: localization for system validators messages. Refs #2835
FirewallRules: run firewall-adjust event as detached task. Refs #2835
nethserver-shorewall-restart: catch error messages and store into Tracker running state. Refs #2835
host-create, host-modify events: reconfigure shorewall when host records change. Refs #2835
/etc/shorewall/rules: bump identifier on rule comment. Refs #2716
/etc/shorewall/rules: empty values replaced by "-", for column count consistency. Refs #2835
Merge branch 'b2835'. Refs #2835