iptables: jump to DOCKER-USER first
iptables: jump to DOCKER-USER first

Fixes #1827

Signed-off-by: Jacob Wen <7568f2e94ed170d8618606da6292179f0e1b678f@oracle.com>

mahak/libnetwork,medallia/libnetwork,abhi/libnetwork,mahak/libnetwork,medallia/libnetwork,fcrisciani/libnetwork,ityangchen/libnetwork,docker/libnetwork,abhi/libnetwork,fcrisciani/libnetwork,allencloud/libnetwork,kolyshkin/libnetwork,ityangchen/libnetwork,kolyshkin/libnetwork,vdemeester/libnetwork,docker/libnetwork,allencloud/libnetwork,vdemeester/libnetwork,abhi/libnetwork,vdemeester/libnetwork,docker/libnetwork,mahak/libnetwork,kolyshkin/libnetwork,medallia/libnetwork