warn the user when docker is not locally installed

also update the documentation
also support ipv6

and grab first vm ip for connection
stash conflict.
use ssh ControlMaster to differenciate channels

this fixes --vm that was broken
use a dynamic port for remote vms

This should go towards allowing concurrent docker usage with less bugs.
fix unixpipe failure with unix socket connection

close child fd from parent to avoid blocking client
catch and display socket errors nicely
Use DOCKER_HOST and be verbose about that

using DOCKER_HOST after tunnel setup is an option for the user.
refactor brainfuck
add a few style fixes
Merge pull request #11 from kalou/docker-fixes

Various fixes for gandi vm docker command