title: Sorting by a GenericIPAddressField in Django admin site
body: <p>How can I numerically sort a model by a GenericIPAddressField in Django's admin site?</p>
  
  <p>Using Meta.ordering in the model sorts it like this:</p>
  
  <ul>
  <li>192.168.1.1</li>
  <li>192.168.1.15</li>
  <li>192.168.1.9</li>
  </ul>
  
  <p>But I want it sorted like this:</p>
  
  <ul>
  <li>192.168.1.1</li>
  <li>192.168.1.9</li>
  <li>192.168.1.15</li>
  </ul>