More easily attach to container using nsinit and container name

attach.sh

#!/bin/bash

attach_container() {
  id=$(docker inspect --format '{{ .ID }}' $1)
  cd /var/lib/docker/execdriver/native/${id}
  if [ ! -z $2 ]; then
    prog="${*:2}"
  else
    prog=bash
  fi
  nsinit exec $prog
}

attach_container $1 ${*:2}