Support for django-app-template, or a version of it

[GriceTurrble]

Would like to merge my own griceturrble/django-app-template into this site template, so that those same features become a part of the bigger picture.

Requires copying code from there to here, particularly to get rid of all the repo-specific files (which I tried eliminating with the actions that generate a release artifact). Also need some considerable updates to docs to show how to use it.