django 1.7

Hm. The documentation [says](https://docs.djangoproject.com/en/1.7/topics/forms/modelforms/#selecting-the-fields-to-use): “This fundamental approach is known to be much less secure and has led to serious exploits on major websites (e.g. GitHub).” So we might use the explicit way so we do not have to “guarantee [that] these security concerns do not apply to [us]”.