This generates an ID string for calls to Mount/Unmount, allowing drivers
to differentiate between two callers of `Mount` and `Unmount`.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
The `Status` field is a `map[string]interface{}` which allows the driver to pass
back low-level details about the underlying volume.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>