Software release installation status does not depend anymore on Purchase
Packing List state.

Sale Order's have to be ordered, as they are created as planned.

The next step is slap call for requesting software installation,
so there is no need to mimic it internally.

See 0226c889

No being able to allocation Software Instance should not prevent allocating slave instance.

The information is cached/stored as #access by SlapTool and not as #ok on memcached.

Fixed request to behave as master (request defined by requester and request name(partition_reference))

It allows seemless multiple calls via SlapTool.

Wrong code has been "fixed".

This cache will be dropped in next development iteration, so the easiest
approach is taken for tests to pass: just not use cache during testing.