Clusters that have an admission controller that requires containers
to run as a non-root user need the default user of the image to be
declared as a numeric uid, so that the constraint can be applied
prior to starting the container.
Change "USER root" to "USER 0" and "USER coder" to "USER 1000"
* Create a set of base images that other images use to reduce duplication
* Use docker driver to allow using locally built and cached images
* Add lsb-release, ca-certificates, and locales (or equivalent packages) to base images
* Add pip3 to ubuntu