ECOM-7207

Upgrading to Dogwood is complicated, because we have to make two
intermediate stops along the way: once at the end of Django 1.4 to
migrate the databases using South, then to the beginning of Django 1.8
to apply --fake-initial migrations.  Then we can upgrade to the Dogwood
release that we actually want.

This will include the latest updates and removes an additional update later on.

This still needs to be more thouroughly tested with fullstack.

Deal with the upgrade of celery and permissions in the rbenv.