This adds support for specifying the scheduler name, volumes (and
volume mounts), and additional metadata labels to the Kubernetes
and OpenShift (and OpenShift pods) drivers.
This also extends the k8s and openshift test frameworks so that we
can exercise the new code paths (as well as some previous similar
settings). Tests and assertions for both a minimal (mostly defaults)
configuration as well as a configuration that uses all the optional
settings are added.
Change-Id: I648e88a518c311b53c8ee26013a324a5013f3be3
9bf44b4a4c