Implement 'Nodes Network' test for GKE; add optional verbose SSH.

hack/ginkgo-e2e.sh

@@ -89,7 +89,7 @@ fi
 export PATH=$(dirname "${e2e_test}"):"${PATH}"
 "${ginkgo}" "${ginkgo_args[@]:+${ginkgo_args[@]}}" "${e2e_test}" -- \
   "${auth_config[@]:+${auth_config[@]}}" \
-  --host="https://${KUBE_MASTER_IP-}" \
+  --host="https://${KUBE_MASTER_IP:-}" \
   --provider="${KUBERNETES_PROVIDER}" \
   --gce-project="${PROJECT:-}" \
   --gce-zone="${ZONE:-}" \