X-Real-IP is not needed

[collinanderson]

gunicorn and apache-mod-rpaf both use X-Forwarded-For instead

[epicserve]

This article explains why you need both X-Real-IP and X-Forwarded-For, http://distinctplace.com/infrastructure/2014/04/23/story-behind-x-forwarded-for-and-x-real-ip-headers/.