manage-offline-container-images.sh

Fixes bug for retrieving images with tags containing image digests.
Script now gets images from jobs and cronjobs as well.
New env variable DESTINATION_REGISTRY to push to another registry
instead of local registry.
New env variable IMAGES_FROM_FILE to pull images listed in a file
instead of getting images from a running k8s environment.
New env variable REGISTRY_PORT to override port (default is 5000).