travis: update Go 1.7 to rc5
travis: update Go 1.7 to rc5

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