New variable kubernetes_cluster_domain

Use cluster_domain/domain variable consistently across all templated files.
All kubeconfig fields contain cluster domain for uniqueness.

Using kubernetes_cluster_domain param now to allow physical servers
to have a different domain from kubernetes cluster if necessary, but
the default keeps them the same.

Change-Id: Ic1e571dc92166b8b603214367f10382fb0ff04b7
diff --git a/metadata/service/pool/single.yml b/metadata/service/pool/single.yml
index 62e5911..e5826c3 100644
--- a/metadata/service/pool/single.yml
+++ b/metadata/service/pool/single.yml
@@ -20,7 +20,7 @@
       address: 0.0.0.0
       cluster_dns: 10.254.0.10
       allow_privileged: True
-      cluster_domain: cluster.local
+      cluster_domain: ${param:kubernetes_cluster_domain}
       kubelet:
         config: /etc/kubernetes/manifests
         allow_privileged: True