Add the basic test case iptable

*A bacis class iptable_base for adding case in the future
*Subcase iptable_remove to check if container's iptable rules removed after stop.

It's okay to assume IP tables rules were added by the time the call to ``execute()`` (above) returned.  Maybe just gather the list and make sure all the devices are present:

    rules = utils.run('iptables -L -n -v')
    self.logdebug("Iptables rules:\n%s\n", rules)
    for net_device in self.sub_stuff['net_devices']:
        self.failif(net_device not in rules)

If the rules aren't appearing right away, then the test can wait on something happening from the container, like a ``--cidfile=`` appearing.  But I would hope this is not necessary, docker should add the rule before the contained command executes.