title: auth_user error with Django 1.8 and syncdb / migrate
body: <p>When upgrading to Django 1.8 (with zc.buildout) and running syncdb or migrate, I get this message:</p>
  
  <p><code>django.db.utils.ProgrammingError: relation "auth_user" does not exist</code></p>
  
  <p>One of my models contains django.contrib.auth.models.User:</p>
  
  <pre><code>user = models.ForeignKey(
      User, related_name='%(app_label)s_%(class)s_user',
      blank=True, null=True, editable=False
  )
  </code></pre>
  
  <p>Downgrading to Django 1.7 removes the error.  Do I have to include the User object differently in Django 1.8?</p>