implement ipset ip/net groups

This implement ipset groups of ips or network in groups.fw.

groups.fw
---------
[ipgroup ipgroup1]

192.168.0.1
192.168.0.2
192.168.0.3

[ipgroup ipgroup2]

192.168.0.3
192.168.0.4

[netgroup netgroup1]

192.168.0.0/24
10.0.0.0/8

Signed-off-by: Alexandre Derumier <aderumier@odiso.com>