plan to save images into registry

[rwaffen]

References:

• https://github.com/voxpupuli/beaker-hostgenerator/blob/master/lib/beaker-hostgenerator/hypervisor/docker.rb
• https://github.com/voxpupuli/voxpupuli-acceptance/blob/master/lib/voxpupuli/acceptance/spec_helper_acceptance.rb#L21-L22
• https://github.com/voxpupuli/puppet_metadata/blob/master/bin/metadata2gha

We want to have the possibility to generate images with ssh and puppet agent from hostgenerator/metada os list and save them into registry for reuse. atm images are build on the fly and this is timeconsuming.