First version of libvirt firewalld patch

[Thomas Woerner]

Hello,

here is the first version of the firewalld patch for nwfilter. 
"firewall-cmd --direct --passthrough {ipv4|ipv6|eb} args" is used as a 
replacement for iptables, ip6tables and ebtables.

The rules are passed through to netfilter without processing and saving 
them. This means that the rules are gone if firewalld will be reloaded 
or restarted. Therefore I'd like to add automatic firewalld activation, 
deactivation and reactivation detection (using a dbus watch) in case of 
firewalld start, stop and restart/reload.

Thomas