Use k8s.gcr.io instead of gcr.io/google_containers

* Kubernetes recommends using the alias to fetch images
from the nearest GCR regional mirror, to abstract the use
of GCR, and to drop names containing 'google'
* https://groups.google.com/forum/#!msg/kubernetes-dev/ytjk_rNrTa0/3EFUHvovCAAJ

bare-metal/container-linux/kubernetes/bootkube.tf

@@ -1,6 +1,6 @@
 # Self-hosted Kubernetes assets (kubeconfig, manifests)
 module "bootkube" {
-  source = "git::https://github.com/poseidon/terraform-render-bootkube.git?ref=b408d80c593cef46aac49bd98c02dac9c7d7b7d8"
+  source = "git::https://github.com/poseidon/terraform-render-bootkube.git?ref=33e00a6dc5cdf2744b0f607329c1566ae8e5fde9"
 
   cluster_name          = "${var.cluster_name}"
   api_servers           = ["${var.k8s_domain_name}"]

bare-metal/container-linux/kubernetes/cl/controller.yaml.tmpl

@@ -118,7 +118,7 @@ storage:
       mode: 0644
       contents:
         inline: |
-          KUBELET_IMAGE_URL=docker://gcr.io/google_containers/hyperkube
+          KUBELET_IMAGE_URL=docker://k8s.gcr.io/hyperkube
           KUBELET_IMAGE_TAG=v1.10.0
     - path: /etc/hostname
       filesystem: root

bare-metal/container-linux/kubernetes/cl/worker.yaml.tmpl

@@ -81,7 +81,7 @@ storage:
       mode: 0644
       contents:
         inline: |
-          KUBELET_IMAGE_URL=docker://gcr.io/google_containers/hyperkube
+          KUBELET_IMAGE_URL=docker://k8s.gcr.io/hyperkube
           KUBELET_IMAGE_TAG=v1.10.0
     - path: /etc/hostname
       filesystem: root