Add support for selinux and podman to MLCube 2.0.

[dfeddema]

podman run --rm -ti --volume /root/mlcube_2.0/mlcube_examples/mnist/workspace/logs/:/mlcube_io2/:z --entrypoint=/bin/bash mlcommons/mnist:0.0.1

Add a ":z"option to the volume mount, which tells Podman to relabel the volume's content to match the label inside the container. And the SELinux problem is solved. Otherwise you will get "Permission denied" error when you attempt to create files in /mlcube_io2. (above).

[bkmgit]

Maybe worth using Udica?

[bkmgit]

Maybe Podman should have its own configuration? WIP #232