iptables-restore error when table not loaded.

When adding openstack rules, if a table module is not loaded,
the resulted file doesn't include the section for the missing
table, making new rules added to it, out of place and
a no valid file for iptables-restore

Fixes bug #1103436

Change-Id: I34ae51a23efec57bfec37b8fa378d043fcf62d70
Merge "iptables-restore error when table not loaded."