standardize install and configuration of docker

This makes the default OS Ubuntu 14.04 amd64 and uses a "standard" method of installing and configuring Docker.  This will handle installing Docker as well as setting the default options to be unified across providers.  It also makes for an easier upgrade path as drivers simply need to call `InstallDocker`.
Actually you are correct.  However, it appears that the install script is spitting stuff to stderr.  This is without the DEBUG check:

```
INFO[0069] Installing and configuring Docker...
sudo: unable to resolve host ubuntu1404x64
+ [ https://get.docker.com/ = https://get.docker.com/ ]
+ sh -c apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 36A1D7869245C8950F966E92D8576A8BA88D21E9
gpg: requesting key A88D21E9 from hkp server keyserver.ubuntu.com
gpg: key A88D21E9: public key "Docker Release Tool (releasedocker) <docker@dotcloud.com>" imported
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)
+ sh -c echo deb https://get.docker.com/ubuntu docker main > /etc/apt/sources.list.d/docker.list
+ sh -c sleep 3; apt-get update; apt-get install -y -q lxc-docker
+ sh -c docker version
INFO[0110] "machine-test-do" has been created and is now the active machine. To point Docker at this machine, run: export DOCKER_HOST=$(machine url) DOCKER_AUTH=identity
INFO[0110] "machine-test-do" has been created and is now the active machine.
```