Bug 24940: Serials statistics wizard: order vendor list alphabetically

Bug 24940: Serials statistics wizard: order vendor list alphabetically

This patch changes the dropdown from being sorted by aqbookseller.id to
aqbookseller.name

To test:
1) Add at least 2 vendors:
 - First: ZZZZ
 - Second: AAAA
2) Add subscriptions for each of the vendors
3) Check the pull down in the serials statistics wizard and verify it
lists them as ZZZZ, AAAA
4) Apply the patch
5) Re-check the pull down in the wizard and check that the vendors are
now listed AAAA,ZZZZ

Signed-off-by: Devinim <kohadevinim@devinim.com.tr>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>