title: Heroku missing module
body: <p>I'm trying to deploy a simple node.js server to Heroku, but keep running into this error:</p>
  
  <pre><code>Error: Cannot find module 'morgan'
  </code></pre>
  
  <p>I'm using <code>morgan</code> to do some HTTP logging, i have morgan in my <code>package.json</code> under the devDependencies (along with many others)</p>
  
  <pre><code>"devDependencies": {
      "morgan": "~1.5.0"
  }
  </code></pre>
  
  <p>I can do <code>npm install</code> locally and start the server without any issues, but when I deploy to Heroku I keep running into that error once it starts the server.</p>
  
  <p>Is there anything I'm forgetting?</p>