travis: add Go 1.5
travis: add Go 1.5

liron-l/go-dockerclient,bradgignac/go-dockerclient,fsouza/go-dockerclient,jefferai/go-dockerclient,davidstack/go-dockerclient,ybogdanov/go-dockerclient,eliasgs/go-dockerclient,codekitchen/go-dockerclient,samuelkarp/go-dockerclient,cloudimmunity/go-dockerclientx,achanda/go-dockerclient,csrwng/go-dockerclient,davidstack/go-dockerclient,tarsisazevedo/go-dockerclient,bboreham/go-dockerclient,giantswarm/go-dockerclient,lindenlab/go-dockerclient,swagiaal/go-dockerclient,paulbellamy/go-dockerclient,jandre/go-dockerclient,ybogdanov/go-dockerclient,tarsisazevedo/go-dockerclient,daniel-garcia/go-dockerclient,flowlo/go-dockerclient,csrwng/go-dockerclient