Ironic inspector does not support iptables under IPv6 network

[zhengyong]

Under IPv6 network, we should use command 'ip6tables' to config firewall, but we only use command 'iptables' to config firewall, we can see here:

# on branch master ironic_inspector/pxe_filter/iptables.py
class IptablesFilter(pxe_filter.BaseFilter):
    """A PXE boot filtering interface implementation."""

    def __init__(self):
        super(IptablesFilter, self).__init__()
        self.blacklist_cache = None
        self.enabled = True
        self.interface = CONF.iptables.dnsmasq_interface
        self.chain = CONF.iptables.firewall_chain
        self.new_chain = self.chain + '_temp'
        self.base_command = ('sudo', 'ironic-inspector-rootwrap',
                             CONF.rootwrap_config, 'iptables')

this should to fixed.