Docker-machine plugin for oh-my-zsh

• append $DOCKER_MACHINE_NAME and $MACHINE_STATUS to the theme string
• machine name completion
• machine list
• switch -d <machine_name> → cd %machine_name_directory%
• switch -p → pstorm %machine_name_directory%
• working with multiple flags (e.g dmachine switch -d -p)
• run external tools (e.g. docker-machine-dns) via hooks