Enable Mirantis theme in openstack/dashboard

Change-Id: I2da0f36c7b9449a0f5edcb08c43e61f58a537604
diff --git a/classes/cluster/virtual-mcp11-contrail-nfv/openstack/dashboard.yml b/classes/cluster/virtual-mcp11-contrail-nfv/openstack/dashboard.yml
index a68d16d..d568fb4 100755
--- a/classes/cluster/virtual-mcp11-contrail-nfv/openstack/dashboard.yml
+++ b/classes/cluster/virtual-mcp11-contrail-nfv/openstack/dashboard.yml
@@ -6,6 +6,7 @@
 - system.horizon.server.single
 - system.horizon.server.plugin.contrail
 - system.horizon.server.plugin.overrides
+- system.horizon.server.plugin.theme
 - cluster.virtual-mcp11-contrail-nfv
 parameters:
   _param: