travis: remove Go 1.5.4
travis: remove Go 1.5.4

fsouza/go-dockerclient,csrwng/go-dockerclient,davidstack/go-dockerclient,tarsisazevedo/go-dockerclient,davidstack/go-dockerclient,tarsisazevedo/go-dockerclient,paulbellamy/go-dockerclient,csrwng/go-dockerclient