Soft delete resources instead of hard

[Cryptophobia]

From @helgi on September 15, 2016 22:18

When deleting apps / resources in DB we actually do a hard delete but what if we did soft delete? It is easier to trace things through time

http://stefan.haflidason.com/safer-soft-deletion-in-django/
http://www.akshayshah.org/post/django-soft-deletion/

This can be used instead to keep audit log without having any resource around https://github.com/jjkester/django-auditlog (https://github.com/shtalinberg/django-actions-logger is a fork of that) or https://github.com/kajic/django-model-changes, https://pypi.python.org/pypi/django-reversion/2.0.6

Audit log is only useful up to a point if there is no data around to introspect

Copied from original issue: deis/controller#1073