* Using a configmap generator is a bit cleaner because we can store
  the configuration file in a external file rather than inlining it in
  the config map.

* Using a configmap generator also has the advantage that kustomize will
  generate a unique name based on a hash of the content.

  * This has the advantage that if a user updates the config, the hash
    would change so deployments would automatically be redeployed in order
    to pick up the config changes.

* Also update the default image used in the configmap to fix kubeflow#1010

  the jupyter web app config map without the prefix/suffix.