title: Django admin - return the text from a forgeign key as display name
body: <p>I want to have the display name of my drop down in the admin panel to be the location title from the parent model. by default the list shows "SNMPData Object" for all items in the list. </p>
  
  <p>however I want to show the site name, I thought it was as simple as adding self.location but that is throwing the error</p>
  
  <p>error:</p>
  
  <pre><code>coercing to Unicode: need string or buffer, MajorSiteInfoData found
  </code></pre>
  
  <p>code:</p>
  
  <pre><code>class MajorSiteInfoData(models.Model):
      Location = models.CharField(max_length=200)
  
      class Meta:
              verbose_name = "Major Site Locations"
              verbose_name_plural = "Major Site Locations"      
  
      def __unicode__(self):
          return self.Location
  
  class SNMPData(models.Model):   
      Location = models.ForeignKey(MajorSiteInfoData)
      SNMP_AUTH = models.CharField(max_length=200)
      SNMP_PRIV = models.CharField(max_length=200)   
  
      class Meta:
              verbose_name = "SNMP Data"
              verbose_name_plural = "SNMP Data"  
  
      def __unicode__(self):
          return self.Location   
  </code></pre>