Enable Mirantis theme in openstack/dashboard

Change-Id: I2da0f36c7b9449a0f5edcb08c43e61f58a537604
diff --git a/classes/cluster/virtual-mcp11-ovs/openstack/dashboard.yml b/classes/cluster/virtual-mcp11-ovs/openstack/dashboard.yml
index a9cbd60..faeb96f 100644
--- a/classes/cluster/virtual-mcp11-ovs/openstack/dashboard.yml
+++ b/classes/cluster/virtual-mcp11-ovs/openstack/dashboard.yml
@@ -4,6 +4,7 @@
 - system.linux.system.repo.mcp.extra
 - system.linux.system.repo.saltstack.xenial
 - system.horizon.server.single
+- system.horizon.server.plugin.theme
 - cluster.virtual-mcp11-ovs
 parameters:
   _param: