Bug 26582: Add Koha::Acquisition::Basket->close

Bug 26582: Add Koha::Acquisition::Basket->close

This patch adds two methods to Koha::Acquisition::Basket:
- 'closed': that tells if the basket is closed
- 'close': that closes the basket

It inherits the behaviour from CloseBasket (as it actually makes sense).
It improves CloseBasket by wrapping the action inside a transaction. It
uses the $orders->update call with no_trigger as there's no trigger to
trigger and the update can be done on a single DB call.

A new exceptions file is added for basket-related exceptions. The only
specific exception that gets added is
Koha::Exceptions::Acquisition::Basket::AlreadyClosed

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

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>