Fix image snapshot for AWS

[slabasan]

For future tutorials, will need to rely on AWS instances running the image. Ideally, the snapshot will already be running the docker image, so once the instance is booted, the user just has to put the URL in the browser to get the jupyterhub page.

[ilumsden]

After some discussions with @milroy and @dyokelson, we are also going to explore pulling in the same type of Kubernetes setup that the Flux tutorial has. #49 is implementing that.