title: Execute mocha tests through proxy or not with grunt
body: <p>I'd like to configure my mocha tests to be performed behind a proxy or not.
  For example,</p>
  
  <pre><code>grunt test 
  </code></pre>
  
  <p>would execute the tests I have defined in my test folder on localhost (no proxy).</p>
  
  <p>And </p>
  
  <pre><code>export http_proxy=PROXY:PORT
  grunt test mywebsite.com
  </code></pre>
  
  <p>would execute the tests but through a proxy.</p>
  
  <p>Is that possible?</p>