adding a docker registry to the head node

Change-Id: I9509b32c00c097259b83a802ab35f8c529a95947
diff --git a/head-node.yml b/head-node.yml
index 9331078..600d396 100644
--- a/head-node.yml
+++ b/head-node.yml
@@ -2,3 +2,4 @@
   serial: 1
   roles:
     - head-node
+    - registry