Configure k8s services for rolling updates

[gothub]

Rolling updates are support by k8s, as described here. With this capability, new versions of MetaDIG services could be installed without downtime.

[jeanetteclark]

This is mostly implemented, however I did run into an issue with updating the postgres schema yesterday.

@mbjones suggested we have all of the other containers (worker, controller, scorer, scheduler) start with an initContainer that makes sure pg is operational before they start. Here is an example: https://github.com/DataONEorg/dataone-indexer/blob/develop/helm/templates/deployment.yaml#L69

This is likely tied to #354