title: Django proxy admin
body: <p>I'm trying to create separated user for django admin, that has limited permissions instead of regular admin. I know that the best approach will be to use proxy admin, but I'm facing some problems.</p>
  
  <p>I've got models structure, that is unlikely to be changed. Each model inherits from some abstract base model class. And I'm unable to add <code>proxy=True</code> clause. The structure of models looks more or less like that:</p>
  
  <pre><code>class AbstractObject(models.Model):
      @property
      def some_property_that_applies_to_each_child_model(self):
          pass
  
      class Meta():
          abstract = True
  
  class ModelOne(AbstractObject):
      id_field = models.IntegerField(primary_key=True)
      @property
      def some_custom_property(self):
          pass
  
  class ModelTwo(AbstractObject):
      id_field = models.IntegerField(primary_key=True)
      @property
      def some_other_custom_property(self):
          pass
  </code></pre>
  
  <p>now I want to create restricted admin account that can do only some actions that aren't deal with db. I know that I need to add <code>proxy=True</code> in <code>class Meta</code> definition for each model, but it isn't working... I get the error <code>raise typeerror(proxy model %s has no non-abstract model base class. % name)</code> which is quite obvious. Should I create some kind of non-abstract model base mock class and add it to the db tables? </p>
  
  <p>I hope that you will get the idea of what I've encountered </p>