Fix issue where ConfigMap isn't applied to new cluster (#235)

If you are trying to recover a cluster that was deleted, the current
code will not re-apply the ConfigMap because it is already rendered so
kubectl command won't get triggered.

This change adds the cluster endpoint (which should be different when
spinning up a new cluster even with the same name) so we will force a
re-render and cause the kubectl command to run.

aws_auth.tf

@@ -14,6 +14,7 @@ resource "null_resource" "update_config_map_aws_auth" {
 
   triggers {
     config_map_rendered = "${data.template_file.config_map_aws_auth.rendered}"
+    endpoint            = "${aws_eks_cluster.this.endpoint}"
   }
 
   count = "${var.manage_aws_auth ? 1 : 0}"