Gunicorn v19 removed functionality which updated `REMOTE_ADDR` to the value of
the `X-Forwared-For` header if received from a trusted upstream client. This
was a violation of RFC 3875 CGI Version 1.1, and was hence removed.
Close: #1035
PR-URL: #1037
Related: #633
Signed-off-by: Hans Kristian Flaatten <hans.kristian.flaatten@turistforeningen.no>