travis: enable go 1.9 (#992)
travis: enable go 1.9 (#992)


yongtang/coredns,chrisohaver/coredns,ii/coredns,ii/coredns,johnbelamaric/coredns,jremond/coredns,coredns/coredns,jremond/coredns,miekg/coredns,miekg/coredns,johnbelamaric/coredns