Improve support for 0.4.1 and 0.5.0 docker-machine
Improve support for 0.4.1 and 0.5.0 docker-machine

ejones/docker-osx-dev,interactive-pioneers/docker-osx-dev,devotox/docker-osx-dev,brikis98/docker-osx-dev,yoanisgil/docker-osx-dev,styleseat/docker-osx-dev