Add stacklight_environment parameter

This allows Nagios to support several environments.

https://github.com/Mirantis/mk-lab-salt-model/pull/197
diff --git a/nagios/server/init.yml b/nagios/server/init.yml
index b5fea3b..da4dcc4 100644
--- a/nagios/server/init.yml
+++ b/nagios/server/init.yml
@@ -3,6 +3,7 @@
     nagios_notification_email: root@localhost
     nagios_host_dimension_key: nagios_host
     nagios_default_host_alarm_clusters: 00-clusters
+    stacklight_environment: ${_param:cluster_domain}
   nagios :
     server:
       enabled: true
@@ -39,6 +40,7 @@
       dynamic:
         enabled: true
         grain_hostname: 'host'
+        hostname_suffix: ${_param:stacklight_environment}
         hostgroups:
           - target: '*'
             name: All