proposal: add a small set of default labels to the docker base images

[Jim Perrin]

I'd like to propose that a small subset of LABEL values be added to the
Dockerfile, to support the generic labels defined here ->
https://github.com/projectatomic/ContainerApplicationGenericLabels

I think adding name, version, release, architecture, build-date, vendor,
url and summary would be a good default set. There should not be any
impact for running containers with this added meta-data outside atomic,
and would help provide additional information that could be referenced
via atomic or cockpit.

Thoughts?