iptables: support iptables older than 1.4.11
iptables: support iptables older than 1.4.11

this checks the version of iptables, if it's older it'll use an iptables list
command to check if a rule exists, otherwise it'll use the newer -C command

Fixes #91

dcbw/flannel,benbjohnson/flannel,eyakubovich/flannel,bprashanth/flannel,imzhulei/flannel,cusspvz/flannel,lihuanghai/flannel,flynn/flannel,coreos/flannel,eyakubovich/flannel,coreos/flannel,wikimedia/operations-debs-flannel,wikimedia/operations-debs-flannel,coreos/flannel,flynn/flannel,lvlv/flannel,lihuanghai/flannel,adiclepcea/flannel,adiclepcea/flannel,kelcecil/flannel,jonboulle/flannel,ingvagabund/flannel,MohdAhmad/flannel,EverythingMe/flannel,ingvagabund/flannel,bprashanth/flannel,bprashanth/flannel,svdata/flannel,svdata/flannel,imzhulei/flannel,Yhgenomics/flannel,eyakubovich/flannel,wikimedia/operations-debs-flannel,EverythingMe/flannel,imzhulei/flannel,endocode/flannel,lvlv/flannel,cusspvz/flannel,Yhgenomics/flannel,lvlv/flannel,dcbw/flannel,kelcecil/flannel,jonboulle/flannel,svdata/flannel,ingvagabund/flannel,sujitfulse/flannel,cusspvz/flannel,flynn/flannel,sujitfulse/flannel,lihuanghai/flannel,sujitfulse/flannel,benbjohnson/flannel,endocode/flannel,kelcecil/flannel,Yhgenomics/flannel,dcbw/flannel,EverythingMe/flannel,adiclepcea/flannel,jonboulle/flannel,endocode/flannel,MohdAhmad/flannel,benbjohnson/flannel,MohdAhmad/flannel