Change the Job and CronJob YAML manifests to use container image
registry us.gcr.io/k8s-artifacts-prod/descheduler. This is the new
official location for the descheduler container image that is very close
to being all setup.
The k8s YAML manifests for deploying the descheduler as a k8s job were
duplicated across the "examples" and "kubernetes" directories and also
in README.md. This change consolidates the YAML manifests into the
"kubernetes" directory and simplifies the installation instructions for end
users in README.md.
Additionally a k8s CronJob has been added.
