travis: upgrade to Go 1.5.3
travis: upgrade to Go 1.5.3

tsuru/tsuru,ggarnier/tsuru,cezarsa/tsuru,gwmoura/tsuru,ggarnier/tsuru,cezarsa/tsuru,ggarnier/tsuru,guilhermebr/tsuru,gwmoura/tsuru,ArxdSilva/tsuru,ggarnier/tsuru,ArxdSilva/tsuru,Endika/tsuru,tsuru/tsuru,guilhermebr/tsuru,gwmoura/tsuru,tsuru/tsuru,Endika/tsuru,ArxdSilva/tsuru,ArxdSilva/tsuru,tsuru/tsuru,guilhermebr/tsuru,guilhermebr/tsuru,cezarsa/tsuru,Endika/tsuru,cezarsa/tsuru