title: How to tell the Gem File to use a specific local copy of a gem
body: <p>Say I have a gem living happily at:</p>
  
  <ol>
  <li><code>/MyPath/MyGem.gem</code></li>
  </ol>
  
  <p>And I want to use the local and unique gem rather than a gem version from Github, or wherever it fetches it from. </p>
  
  <p>How do I specify I want to use <code>gem "mygem"</code> from <code>/MyPath/MyGem.gem</code></p>