Document tutorial and create convenience script for CLI scan of containers

It would be great to have an end-to-end tutorial on how to scan a container from the CLI, from scratch, possibly using a wrapper script:

We should also support in this:
1. authenticated private docker registry access
2. private docker registry using client certficates

There could be two modes:
1. one where this is calling the API of a pre-installed SCIO
2. one where this is a one-off CLI process starting from nothing installed, and just run that one scan transaction to get the JSON results out