travis: run tests with Go 1.8.3
travis: run tests with Go 1.8.3

Signed-off-by: Gyu-Ho Lee <3454051ee3341eb69bdf6fca40899cdad4d86496@gmail.com>

YuleiXiao/etcd,vimalk78/etcd,bluebreezecf/etcd,cockroachdb/etcd,visheshnp/etcd,sinsharat/etcd,sinsharat/etcd,li-ang/etcd,mickep76/etcd,glevand/coreos--etcd,li-ang/etcd,mqliang/etcd,rnaveiras/etcd,vimalk78/etcd,coreos/etcd,glevand/coreos--etcd,rnaveiras/etcd,dannysauer/etcd,etcd-io/etcd,sebrandon1/etcd,xiang90/etcd,dannysauer/etcd,mqliang/etcd,a-robinson/etcd,whuwxl/etcd,heyitsanthony/etcd,coreos/etcd,cockroachdb/etcd,visheshnp/etcd,armstrongli/etcd,akauppi/etcd,xiang90/etcd,bdarnell/etcd,bdarnell/etcd,a-robinson/etcd,rnaveiras/etcd,mkumatag/etcd,ajityagaty/etcd,bluebreezecf/etcd,gyuho/etcd,etcd-io/etcd,etcd-io/etcd,lorneli/etcd,heyitsanthony/etcd,armstrongli/etcd,ajityagaty/etcd,gyuho/etcd,YuleiXiao/etcd,mkumatag/etcd,akauppi/etcd,whuwxl/etcd,mqliang/etcd,joshix/etcd,joshix/etcd,sebrandon1/etcd,mkumatag/etcd,lorneli/etcd,fanminshi/etcd,fanminshi/etcd,ajityagaty/etcd,mickep76/etcd