api/app: using ResponseWriter.Write instead Fprintf
api/app: using ResponseWriter.Write instead Fprintf

using w.Write instead fmt.Fprintf to
avoid to convert the byte to string.

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