Cloudflare IP forwarding when using getCurrentIP()

HTTP_X_FORWARDED_FOR doesn't always work with Cloudflare,
HTTP_CF_CONNECTING_IP however does.

https://support.cloudflare.com/hc/en-us/articles/200170986-How-does-CloudFlare-handle-HTTP-Request-headers-
Merge pull request #2002 from Contex/development

Cloudflare IP forwarding when using getCurrentIP()