Add stacklight_environment parameter

This allows Nagios to support several environments.

https://github.com/Mirantis/mk-lab-salt-model/pull/197
diff --git a/heka/aggregator/cluster.yml b/heka/aggregator/cluster.yml
index e2ee129..455dbb1 100644
--- a/heka/aggregator/cluster.yml
+++ b/heka/aggregator/cluster.yml
@@ -1,5 +1,6 @@
 classes:
 - service.heka.aggregator.cluster
+- system.heka.server
 parameters:
   _param:
     nagios_default_host_alarm_clusters: 00-clusters
diff --git a/heka/aggregator/single.yml b/heka/aggregator/single.yml
index c252bd6..4b1c71f 100644
--- a/heka/aggregator/single.yml
+++ b/heka/aggregator/single.yml
@@ -1,5 +1,6 @@
 classes:
 - service.heka.aggregator.single
+- system.heka.server
 parameters:
   _param:
     nagios_default_host_alarm_clusters: 00-clusters