Bug 27209: Add Koha::Hold->set_pickup_location

Bug 27209: Add Koha::Hold->set_pickup_location

This patch introduces a method to safely update a hold's pickup
location. It will raise exceptionis if the passed parameters are invalid
or absent.

To test:
1. Apply this patches
2. Run:
   $ kshell
  k$ prove t/db_dependent/Koha/Hold.t
=> SUCCESS; Tests pass
3. Sign off :-D

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>