Added submodules test

tests/apps/gitsubmodules/Procfile

@@ -0,0 +1 @@
+web: bin/node node-js-sample/web.js

tests/apps/gitsubmodules/check_deploy

@@ -0,0 +1,2 @@
+#!/bin/bash
+set -e; output="$(curl -s $1)"; echo $output; test "$output" == "Hello World!"

tests/apps/gitsubmodules/package.json

@@ -0,0 +1,11 @@
+{
+  "name": "node-example",
+  "version": "0.0.1",
+  "dependencies": {
+    "express": "~3.3.4"
+  },
+  "engines": {
+    "node": "0.10.x",
+    "npm": "1.3.x"
+  }
+}

tests/apps/gitsubmodules/pre-commit

@@ -0,0 +1,2 @@
+#!/bin/bash
+git submodule add https://github.com/heroku/node-js-sample.git node-js-sample