Support for emulation of Persistent Volumes via PVCs

[ncresswell]

In the Alpha, we support container persistence via hostpath mapping (which translates to a docker bind mount), which is rarely used in Kubernetes deployments. What is more common is PV's and PVC's coming from a storage class.

To provide standardised support for manifests that expect a PVC, we should emulate a default storage class (docker), make it the default, and then translate PVC's to Docker named volumes, akin to "docker volume create"