Upgrade Django minor version.
Use Django admin.
Folder filters.
Generic model/file update propagation.
Simplify group updates.
Merge branch 'django-admin' of https://github.com/jcushman/perma into jcushman-django-admin
Limit propagated fields; auto-propagate media changes.
I was having problems with the gpg logic. I put more of it behind
the MIRRORING_ENABLED flag
Merge branch 'mirror-generic' of https://github.com/jcushman/perma into jcushman-mirror-generic

Conflicts:
	perma_web/mirroring/tasks.py
Merge pull request #743 from jcushman/group-updates

Simplify group updates.