If we only have a single preference object redirect to it,
        otherwise display listing.

def changelist_view(self, request, extra_context=None):
        """
        If we only have a single preference object redirect to it,
        otherwise display listing.
        """
        model = self.model
        if model.objects.all().count() > 1:
            return super(HTMLSitemapAdmin, self).changelist_view(request)
        else:
            obj = model.singleton.get()
            return redirect(reverse('admin:jmbo_sitemap_%s_change' % \
                    model._meta.module_name, args=(obj.id,)))