travis: run for go 1.5.x and higher
travis: run for go 1.5.x and higher

errcheck does not build on 1.4.x anymore

optiopay/kafka,liftoffio/go-kafka,husio/kafka,liftoffio/go-kafka,husio/kafka,optiopay/kafka,alexcesaro/kafka,zorkian/kafka,danieltahara/kafka,alexcesaro/kafka,zorkian/kafka,danieltahara/kafka,dropbox/kafka,dropbox/kafka