Output the Google network name and self_link

* Allow users to add custom firewall rules for unique cases

google-cloud/container-linux/kubernetes/outputs.tf

@@ -5,3 +5,11 @@ output "controllers_ipv4_public" {
 output "ingress_static_ip" {
   value = "${module.workers.ingress_static_ip}"
 }
+
+output "network_name" {
+  value = "${google_compute_network.network.name}"
+}
+
+output "network_self_link" {
+  value = "${google_compute_network.network.self_link}"
+}