vbox: Delete VM instance when instance is stopped

Before we add support of instance life-cycle management, we delete an instance when
it is stopped. Otherwise, the disk will be full of unused and stopped
instances.

Signed-off-by: Asias He <asias@cloudius-systems.com>
vmw: Delete VM instance when instance is stopped

Before we add support of instance life-cycle management, we delete
an instance when it is stopped. Otherwise, the disk will be full of
unused and stopped instances.

Signed-off-by: Asias He <asias@cloudius-systems.com>
Merge pull request #49 from asias/del

Delete VM instance when instance is stopped