Set up a config option to enable/disable remoteip logging for environments where haproxy is in front of u-r-c and is setting X-Forwarded-For headers from which we can extract real client IPs.

Reviewed-on: https://code.launchpad.net/~deej/ubuntu-repository-cache/add-x-forwarded-for-logging/+merge/367271
Reviewed-by: Ryan Finnie <ryan.finnie@canonical.com>
Reviewed-by: Joel Sing <joel.sing@canonical.com>