Bug 7614: Add a new method Koha::Libraries->pickup_locations

Bug 7614: Add a new method Koha::Libraries->pickup_locations

This patch adds a new method, Koha::Libraries->pickup_locations. This method
takes either an item or a biblio as a parameter, and returns the list of
acceptable pickup locations by considering libraries' configuration to act
as a pickup location as well as any branch transfer limits that may apply.

To test:
1. prove t/db_dependent/Koha/Libraries.t

Signed-off-by: Bob Bennhoff <bbennhoff@clicweb.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>