travis: add 1.9.x instead 1.8 go version (#852)
travis: add 1.9.x instead 1.8 go version (#852)


google/trillian,gdbelvin/trillian,codingllama/trillian,daviddrysdale/trillian,daviddrysdale/trillian,Martin2112/trillian,RJPercival/trillian,codingllama/trillian,RJPercival/trillian,Martin2112/trillian,AlCutter/trillian,gdbelvin/trillian,google/trillian,daviddrysdale/trillian,AlCutter/trillian,Martin2112/trillian,gdbelvin/trillian