Bump Docker to v0.9.1. Tested pulling, committing, pushing.

Docker is on Version 0.9.1 now, and I'd like to use it.

I tested this package by pulling an image, ssh-ing into it, installing a bunch of stuff, starting a web server, curl-ing it, exiting, committing it, and pushing it, as in [this tutorial](https://www.openshift.com/blogs/day-21-docker-the-missing-tutorial).

What do you think about merging this? Is this the right destination branch?