Bug 12252: Include item data only in extended mode

Bug 12252: Include item data only in extended mode

Previous patches attached to this bug have been refactored to merge bug
3206 and bug 13568 features. So OAI server must be carrefully tested to
ensure that there is no regression in this area: deleted records and
resumption token.

This last patch fixed the way items are returned. They are returned only
if OAI server operates in extended mode, and specifically for format
having the parameter include_item set to 1 (true). For example this
configuration file set via OAI-PMH:ConfFile syspref will return items:

Signed-off-by: Signed-off-by: Gaetan Boisson <gaetan.boisson@biblibre.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@unc.edu.ar>