title: intern-geezer never responding on BrowserStackTunnel
body: <p>I am trying to get intern-geezer <em>(so far tested on 2.0.1 and 2.1.1)</em> to work so I can perform tests on IE8 as well.
  Currently I am trying to run tests on BrowserStack but unfortunately the test script seems to freeze and never return a response, so I have to stop the process manually.</p>
  <p>My configuration is:</p>
  <h3>test/simpleTest.js</h3>
  <pre><code>define(['intern!object', 'intern/chai!assert'], function (registerSuite, assert) {
      registerSuite({
          name: 'simpleTest',
          sum: function () { assert.strictEqual(2 + 2, 4, 'Should sum'); }
      });
  });
  </code></pre>
  <h3>test/intern-geezer.js</h3>
  <pre><code>define({
      proxyPort: 9000,
      proxyUrl: 'http://localhost:9000/',
      capabilities: { 'selenium-version': '2.41.0' },
      environments: [
          { browserName: 'internet explorer', version: '9',  platform: 'WINDOWS' }
      ],
      tunnel: 'BrowserStackTunnel',
      suites: [ 'test/simpleTest' ],
      excludeInstrumentation: /^(?:test|node_modules)\//
  });
  </code></pre>
  <p>Then calling <code>intern-runner</code></p>
  <pre><code>./node_modules/intern-geezer/bin/intern-runner.js config=test/intern-geezer.js 
  Listening on 0.0.0.0:9000
  Starting tunnel...
  BrowserStackLocal v3.3
  Ready
  Initialised internet explorer 9 on WINDOWS
  </code></pre>
  <p>Then it keeps there forever doesn't matter what the environment is.</p>
  <p>when checking BrowserStack for Exceptions, it seems this is the last operation step to run before it freezes:</p>
  <pre><code>Get URL⇒ http://localhost:9000/__intern/client.html?config=test%2Fintern-geezer.js&amp;reporters=webdriver&amp;functionalSuites=undefined&amp;suites=test%2FsimpleTest&amp;baseUrl=%2F&amp;sessionId=f07e36f7e73786173ee0cfa98feb7e4b9bff3e2c
  </code></pre>
  <p>Any ideas?
  <em>Those tests work fine when using master branch of intern</em></p>