Add ability to load balance TCP applications on AWS

* Add ability to load balance TCP applications (e.g. NodePort)
* Output the network load balancer ARN as `nlb_id`
* Accept a `worker_target_groups` (ARN) list to which worker
instances should be added
* AWS NLBs and target groups don't support UDP

aws/container-linux/kubernetes/workers/workers.tf

@@ -19,6 +19,7 @@ resource "aws_autoscaling_group" "workers" {
   target_group_arns = [
     "${aws_lb_target_group.workers-http.id}",
     "${aws_lb_target_group.workers-https.id}",
+    "${var.target_groups}",
   ]
 
   lifecycle {