Bug 26908: Restore ability to view and select EDI plugins for a vendor account

Bug 26908: Restore ability to view and select EDI plugins for a vendor account

Test Plan:
1) Install an EDI plugin
2) Browse to edi_accounts.pl, create or edit an account
3) Note the plugins pulldown is missing
4) Apply this patch
5) Restart all the things!
6) Reload the page
7) Note the pulldown is back!

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>