Returns the leaf class no matter where the calling instance is in the inheritance hierarchy.
        Inspired by http://www.djangosnippets.org/snippets/1031/

def as_leaf_class(self):
        """
        Returns the leaf class no matter where the calling instance is in the inheritance hierarchy.
        Inspired by http://www.djangosnippets.org/snippets/1031/
        """
        try:
            return self.__getattribute__(self.class_name.lower())
        except AttributeError:
            content_type = self.content_type
            model = content_type.model_class()
            if(model == ModelBase):
                return self
            return model.objects.get(id=self.id)