Implement run command

[vdemeester]

Carrying #45, add a basic run command (with no flags for now). 🐨

# libcompose run <service> <command>
$ ~docker/libcompose/libcompose-cli run web ls
WARN[0000] Note: This is an experimental alternate implementation of the Compose CLI (https://github.com/docker/compose) 
bin  boot  dev  etc  home  lib  lib64  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var
$ ~docker/libcompose/libcompose-cli run web /bin/sh
WARN[0000] Note: This is an experimental alternate implementation of the Compose CLI (https://github.com/docker/compose) 
# ls
bin  boot  dev  etc  home  lib  lib64  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var
# echo foo > /bar    
# cat bar
foo

This is the first step to have a run command that is acting the same as docker-compose. I imported go-dockerpty in a non academic way (and clean it up) as it was not compiling under windows and redefining stuff that are already available on docker/docker/pkg/…. I'll probably make a PR to the repos and vendor it if it makes it and we think it's better to do.

• Need to fix/add some integration tests.

🐸
Signed-off-by: Frederic Branczyk fbranczyk@gmail.com

[vdemeester]

Will reimplement that with engine-api, should be simpler.