Support dynamic provisioning?

[stevefan1999-personal]

Since resizing persistent volumes in k8s is isomorphic to setting a bigger quota on a dataset for ZFS, I think this is pretty doable, sadly I had limited golang knowledge and couldn't really do it on my own.

[asteven]

JFYI: I'm deprecating this in favor of zfs-provisioner which is doing the same thing but is written in python.