Bug 11179: make OPAC course details page display status of checked out items correctly

Bug 11179: make OPAC course details page display status of checked out items correctly

If an item is listed for a course and is checked out, the item will
still show as being available from the course details page which lists
all the items that are part of a course. This is due to the way the
course reserves system handles items and issues separately, while
item-status.inc assumes the due date has been embedded in items.datedue

Test Plan:
1) Create a course
2) Add an item to that course
3) Check the item out to a patron
4) View the course details from the opac
5) Note the status says "Available"
6) Apply this patch
7) Repeat step 4
8) Note the status no longer says "Available"

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>