title: Reorder users in django auth
body: <p>I have a model that has a ForeignKey to the built-in user model in <code>django.contrib.auth</code> and I'm frustrated by the fact the select box in the admin always sorts by the user's primary key.</p>
  
  <p>I'd much rather have it sort by username alphabetically, and while it's my instinct not to want to fiddle with the innards of Django, I can't seem to find a simpler way to reorder the users.</p>
  
  <p>The most straightforward way I can think of would be to dip into my Django install and add</p>
  
  <pre><code>ordering = ('username',)
  </code></pre>
  
  <p>to the Meta class of the User model.</p>
  
  <p>Is there some kind of monkeypatching that I could do or any other less invasive way to modify the ordering of the User model?</p>
  
  <p>Alternatively, can anyone thing of anything that could break by making this change?</p>