title: ember-cli test not working with phantomjs in docker
body: <p>When running <code>ember test --host 172.17.0.2 --test-port 4450</code>, I'm getting the following error.</p>
  
  <p><code>Error: Browser failed to connect within 30s. testem.js not loaded?</code></p>
  
  <p>Since I'm using a docker container I'm assuming I need to update the host and port to the open docker host and port. </p>
  
  <p>This is my <code>testem.js</code> file</p>
  
  <pre><code>/*jshint node:true*/
  module.exports = {
    "framework": "qunit",
    "test_page": "tests/index.html?hidepassed",
    "phantomjs_debug_port": 4500,
    "disable_watching": true,
    "launch_in_ci": [
      "PhantomJS"
    ],
    "launch_in_dev": [
      "PhantomJS",
      "Chrome"
    ]
  };
  </code></pre>