Fix environment bug,version of golang should be 1.4+, add reminding in Readme.md
Fix environment bug,version of golang should be 1.4+, add reminding in Readme.md

rosenhouse/cni,containernetworking/plugins,tangle329/cni,steveeJ/cni,containernetworking/cni,jonboulle/cni,appc/cni,squaremo/cni,Symmetric/cni,tangle329/cni,kad/cni,mcastelino/cni,dcbw/cni,zenlinTechnofreak/cni,murat1985/cni,tomdee/cni,NeilW/cni,squeed/plugins,containernetworking/cni,achanda/cni,squaremo/cni,steveeJ/cni,appc/cni,aanm/cni,luxas/cni,aanm/cni,NeilW/cni,mcastelino/cni,luxas/cni,squeed/plugins,rosenhouse/cni,murat1985/cni,zenlinTechnofreak/cni,achanda/cni,jonboulle/cni,tomdee/cni,dcbw/cni,kad/cni,Symmetric/cni,containernetworking/plugins