Properly handle multiple X-Forwarded-For addresses in runner IP
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24624 extracted the X-Forwarded-For address directly, but this didn't consider the case where multiple proxies are in the chain. To fix this, we use the Rails implementation to filter trusted proxies, as documented by Grape: https://github.com/ruby-grape/grape#remote-ip
Edited by Stan Hu