Using `settings.AUTH_USER_MODEL`
Using `settings.AUTH_USER_MODEL`

Per @jbradberry's recommendations, this changes the parameters of the `created_by` and `modified_by` `ForeignKey` fields to use settings.AUTH_USER_MODEL.

caktus/django-file-picker,caktus/django-file-picker,caktus/django-file-picker,caktus/django-file-picker