ARCH-220

ARCH-193

18.0 seems to be doing a different thing with REMOTE_ADDR.

Putting this back to the last working version in production.

There is a breaking change in gunicorn 19 which changes
the behavior of the `REMOTE_ADDR` request meta info. It
no longer correctly passes through the value of X-Forwarded-For
if that header is present.

This resulted in making anything that looked at this attribute
think that all requests were coming from 127.0.0.1

This broke the django-ratelimit-backend library which relies on
this feature to determine if a user has had too many login attempts.

Gunicorn Change Log: http://docs.gunicorn.org/en/stable/2015-news.html

There are issues in the newest version that we don't want to pick up yet.

We're quite far behind, let's start by just looking at the treadmill.

PLAT-2254

There was an issue with migrations on sandboxes.

This reverts commit 58f6e925