build-yocto: First attempt at Dockerfile
Add instructions for building and running Docker image
Add scripts to build and run container
Install poky as root

Waiting for Docker to implement user-based volumes
(or at least me to understand Docker more...)

Signed-off-by: Gianpaolo Macario <gianpaolo_macario@mentor.com>
Explain how to use the container
Cleanup commented lines
Merge pull request #21 from gmacario/build-yocto

Build tool for Yocto Project 1.6