Bug 15519: Warns when creating a basket

 Bug 15519: Warns when creating a basket

To test:
1) Reproduce warn following steps above
2) Apply patch
3) Create a new basket and click Save. Do not add any items
4) Notice warn is gone
5) Click 'Delete this basket' and confirm that the validation message reads: "Are you sure you want to delete this basket?" Click cancel.
6) Add an order to the basket, then click 'Delete this basket'. Confirm the validation message gives more information and more delete options.

Followed test plan, works as expected.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan A Gallagher <brendan@bywatersolutions.com>