kernel: netfilter: add IPVS kernel module support

IPVS (IP Virtual Server) implements transport-layer load balancing inside
the Linux kernel, so called Layer-4 switching. IPVS running on a host acts
as a load balancer at the front of a cluster of real servers, it can direct
requests for TCP/UDP based services to the real servers, and makes services
of the real servers to appear as a virtual service on a single IP address.

This change adds the following kmod packages
- kmod-nf-ipvs
- kmod-nf-ipvs-ftp
- kmod-nf-ipvs-sip

Signed-off-by: Mauro Mozzarelli <mauro@ezplanet.org>
Signed-off-by: Florian Eckert <fe@dev.tdt.de>