Integrate buster and docker container engine

Heyo, 

I wanted a one-off command that could install+run buster. This does that using docker, which acts as a lightweight virtual environment. It 1) installs buster 2) downloads the site 3) runs buster and 4) deploys.
The primary advantage is anyone with docker installed can now use buster on and site with this one command, without changing their system at all. Github tokens are used to avoid people accidentally putting their private key online. There is enough documentation added to explain how to run this while avoiding imposing on people not interested. 

I have pushed a docker image to hamiltont/buster, but the docs I added reference axitkhurana/buster. You can easily register on index.docker.io and point them to your buster repository to have a "trusted build" performed (e.g. they clone your repo and build the container using the Dockerfile). 

I've also added a setup-clone run mode that will perform setup using `git clone` instead of `git init`. This may be better if done as an option of setup (e.g. `buster setup --clone` instead of `buster setup-clone`).
There is one TODO left in the setup-clone method, I'm not very familiar with GH pages so I may have misunderstood how to properly treat master/gh-pages e.g. a checkout may be needed here.