[Apache] LogFormat with X-Forwarded-For

If you use apache behind a reverse-proxy you need to modify the combined log format to use the X-forwarded-For header. Simply replace:

LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined

by

LogFormat "%{X-Forwarded-For}i %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined