Add short names for Volume Snapshot CRDs

This allows end users to run `kubectl get vs`, for example, instead of
`kubectl get volumesnapshot`. The following short names have been
implemented:

* `VolumeSnapshot` - `vs`
* `VolumeSnapshotContent` - `vsc`, `vscs`
* `VolumeSnapshotClass` - `vsclass`, `vsclasses`

client/config/crd/snapshot.storage.k8s.io_volumesnapshots.yaml

@@ -14,6 +14,8 @@ spec:
     kind: VolumeSnapshot
     listKind: VolumeSnapshotList
     plural: volumesnapshots
+    shortNames:
+    - vs
     singular: volumesnapshot
   scope: Namespaced
   versions: