Check for existence of docker-compose when using dind

[pigmej]

There should be check if docker-compose is present on the system, it can be installed with curl -L https://github.com/docker/compose/releases/download/1.8.0/docker-compose-uname -s-uname -m > /some/file

[ivan4th]

As of now, in 'home' mode it just installs docker-compose 1.8.0 into ~/.k8s-devbox/bin. Will add check to see whether the system already has docker-compose 1.8.0+.