title: Update Auth Model from a deprecated version of Django
body: <p>
  I have the following deprecated code:</p>
  
  <pre class="lang-py prettyprint-override"><code>class samberos(User):
      objects = UserManager()
      backstage = models.BooleanField(default=False, help_text="Si el sambero esta activo, pero no tocando instrumentos ... ")
      dni = models.CharField(max_length=10, blank=True, null=True)
      phone = models.CharField(max_length=9, blank=True, null=True)
      movil = models.CharField(max_length=9, blank=True, null=True, help_text="Este es el numero para los SMS")
      instrumento = models.ForeignKey(instrumentos)
      def url(self):
              return u'&lt;a href="/samberos/' + self.username + u'/" title="' + self.username + u'" rel="gb_page_center[400, 210]"&gt;' + self.username + u'&lt;/a&gt;'
      class Meta:
              ordering = ['username']
              verbose_name_plural = "samberos"
              verbose_name = "samberos"
  </code></pre>
  
  <p>And I want to update it to a newer version of django with is not supported at this moment and don't want to lost the users. How can I do it?</p>
  
  <p>Now I running the version 1.8 and when I ran the server I got the following error:</p>
  
  <pre class="lang-py prettyprint-override"><code>ERRORS:
  actuaciones.samberos.user_ptr: (fields.E301) Field defines a relation with the model 'auth.User', which has been swapped out.
      HINT: Update the relation to point at 'settings.AUTH_USER_MODEL'.
  </code></pre>
  
  <p>The version of django used to create this code was 1.2 and was working fine with 1.4</p>