title: django user model and custom primary key field
body: <p>Django by default makes a primary key field on each model named "<code>id</code>", with a type of <code>AutoField</code>. On my models, I'm overriding this to use a custom <code>UUIDField</code> as the primary key by using the "<code>primary_key</code>" attribute. I would also like the <code>User</code> model in <code>django.contrib.auth</code> to have a <code>UUIDField</code> as the primary key, but this doesn't seem to be possible without changing the <code>User</code> model source code.</p>
  
  <p>Is there any recommended way to approach this problem?</p>