Bug 24386: Prevent double form submission on adding orders to basket from a file

Bug 24386: Prevent double form submission on adding orders to basket from a file

To test:
 1 - Have a marc record file
 2 - Go to Acquisitions, find a vendor, then an open basket
 3 - Add to basket from a new file (if you already have one staged you can choose that instead)
 4 - Import the file, then add to basket
 5 - On the page where you select the records and set info select a record, set matching to 'Do not check' fill in the fund for the order
 6 - When ready, click save as many times as you can
 7 - When you go to the basket there are many copies of the order added
 8 - Don't despair, apply the patch
 9 - Repeat above
10 - When ready to add orders, click furiously
11 - The order is only added once!
12 - Success!

Signed-off-by: Sally <sally.healey@cheshiresharedservices.gov.uk>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>