add test to validate server_tokens is off

tests/unit/nginx-vhosts.bats

@@ -4,15 +4,23 @@ load test_helper
 
 setup() {
   create_app
-  setup_test_tls
-  deploy_app
 }
 
 teardown() {
   destroy_app
 }
 
+@test "nginx (no server tokens)" {
+  deploy_app
+  run /bin/bash -c "curl -s -D - $(dokku url $TEST_APP) -o /dev/null | egrep '^Server' | egrep '[0-9]+'"
+  echo "output: "$output
+  echo "status: "$status
+  assert_failure
+}
+
 @test "nginx:build-config (with SSL CN mismatch)" {
+  setup_test_tls
+  deploy_app
   run /bin/bash -c "dokku domains $TEST_APP | grep node-js-app.dokku.me"
   echo "output: "$output
   echo "status: "$status