Extension Schema for Docker

[wmunyan]

Added a number of tests and supporting information in order to assess the configuration of Docker containers/images.

The "execps_test" mirrors the output of the unix "process58_test", but within a docker container/image
The "info_test" examines a "flattened" output from the "docker info" command
The "keyedinfo_test" examines the full hierarchical output from the "docker info" command
The "inspect_test" examines the output of the "docker inspect" command
The "process_test" examines the output of the "docker ps" command
The "version_test" examines the output of the "docker version" command

[mpreisler]

The names of the tests are too generic, I suggest caling them containerinfo_test, containerinspect_test, etc.. or something like that.

Can info_test or keyed_info test query which keys the container image was signed with? How does it work?

How can I query container image labels, which test would I use?

The tests are very docker specific, historically OVAL tries to be technology agnostic if possible. Could we make the tests more generic to also handle rocket and other container tech?

EDIT: This is my much less extensive proposal, can be used for inspiration #147 I am OK with going forward with your proposal as long as it fulfills my requirements.