Add IPv6 support to configNetwork

This patch add IPv6 functionality to network configuration. We want to
run every device as dual stack device so IPConfig now uses IPv4 AND
IPv6(or one of them).

This patch was built on Hunt Xu's patch 11741.

Change-Id: I8ed056b683f0cb893b2edcf1ae673c64ce5cd18c
Signed-off-by: Petr Sebek <psebek@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/18284
Reviewed-by: Dan Kenigsberg <danken@redhat.com>