Set Elasticsearch cluster.initial_master_nodes for v7 (#1091)
Set Elasticsearch cluster.initial_master_nodes for v7 (#1091)

In the Elastic Stack for Elasticsearch pillar, set
cluster.initial_master_nodes if the version of Elastic Stack is 7 or
above.

This setting has been introduced with version 7 and the cluster will not
run without it.

mitodl/salt-ops,mitodl/salt-ops