iaas/dockermachine: simplify code
iaas/dockermachine: simplify code

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