Needed to retrieve the changelist url as Folder/File can be extended
        and admin url may change

def _get_post_url(self, obj):
        """
        Needed to retrieve the changelist url as Folder/File can be extended
        and admin url may change
        """
        # Code from django ModelAdmin to determine changelist on the fly
        opts = obj._meta
        return reverse('admin:%s_%s_changelist' %
                       (opts.app_label, opts.model_name),
            current_app=self.admin_site.name)