Currently, RHODS relies on the OpenShift default storage class for RHODS storage purposes (eg. saving notebook files). In some cases, customers may want to use storage options other than the default storage. This story is to enable RHODS admins to configure which storage classes are available to users. If an admin wants to make more than 1 storage class available, users should be able to select the storage class when creating workbenches or NB serving sessions.

Request: "As they have different storage classes for different use cases, they'd like to be able to request a scratch space PVC (for a notebook) using a non-default Storage Class (choosing the wanted SC)
."

Reqs:

1. P0: RHODS admins must be able to configure which storage classes should be available for RHODS users.
   • Must be able to configure storage classes other than the OpenShift default.
   • Must be able to configure a 'default' storage for RHODS. This does not have to be the OpenShift default.
   • Must be able to configure the name of the storage class as it should appear for users if exposed in the end user UI. Note: per Guillaume's comment below, the end user UI should show the admin configured display name as well as the real name. 
2. P0: RHODS users should be able to select from available storage classes based on admin config when creating workbenches or NB serving sessions.
   • If only 1 storage class available, the UI should not present an option for users (since the one available will always be used).
   • If more than 1 available, the UI should start with default configured by admin, but users should be able to select any of the available options.