Use virtio device type.
ex_list_drives -> ex_list_user_drives.
Add ex_list_library_drives method.
If user specifies an installation CD image, use ide instead of virtio device
type.
docs: Add an example which shows how to create a server using an installation
cd.
Use a separate method to detect an installation cd.
No need to clone installation CDs, update docstring.
docs: Add example.
Add test for ex_list_library_drives method.