Bug 2341: items marked 'on order' not reserveable from search results

Bug 2341: items marked 'on order' not reserveable from search results

Items created as part of the acquisitions process, and assigned the temporary notforloan value of -1,
cannot be placed on hold from the search results in either the OPAC or staff client (the link is missing).

This patch changes the evaluation of items->notforloan from a Boolean (if $items->{notforloan}) to a comparison
(if $items->{notforloan} > 0).  Any notforloan status with a negative value can therefore be reserved.

Signed-off-by: Nicole Engard <nengard@bywatersolutions.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>