It is used in Hosting skin selection and thus shall override other skins.

When user requested installation of software and later its destruction system
will support case of old client (which will install or just start installation)
and new client (which will delete).

Cover different cases of having already setup packing list.

Method names are self explanatory.

During cleanup deliver all former packing lists.

The first one found is just good enough.

While using old server (which does not send _requested_state on SoftwareRelease)
it defaults to available.

Note: console comes bundled with library, no need to do backward compatibility.

Note: Backward compatible change -- state defaults to 'available'.