Set default value for kube_hyperkube_image_repo

Fixes #1334

roles/kubernetes/node/defaults/main.yml

@@ -51,3 +51,9 @@ kubelet_load_modules: false
 
 ##Support custom flags to be passed to kubelet
 kubelet_custom_flags: []
+
+# This setting is used for rkt based kubelet for deploying hyperkube
+# from a docker based registry ( controls --insecure and docker:// )
+## Empty vaule for quay.io containers
+## docker for docker registry containers
+kube_hyperkube_image_repo: ""