Unhard-coded 'message_queue:port:${_param:rabbitmq_port}'

Change-Id: I9c57a01b4e9f3b5cc03a7618ac8b7af1d227ab76
diff --git a/designate/server/cluster/default.yml b/designate/server/cluster/default.yml
index 112d953..36da38b 100644
--- a/designate/server/cluster/default.yml
+++ b/designate/server/cluster/default.yml
@@ -10,6 +10,7 @@
     cluster_internal_protocol: 'http'
     openstack_mysql_x509_enabled: False
     galera_ssl_enabled: False
+    openstack_rabbitmq_port: 5672
   linux:
     system:
       package:
@@ -59,7 +60,7 @@
           address: ${_param:single_address}
       message_queue:
         engine: rabbitmq
-        port: 5672
+        port: ${_param:openstack_rabbitmq_port}
         members:
         - host: ${_param:openstack_message_queue_node01_address}
         - host: ${_param:openstack_message_queue_node02_address}