Bug 15991: Moving OAI sets actions into a drop-down menu

Bug 15991: Moving OAI sets actions into a drop-down menu

To test:

1) Apply Bug 16014 first
2) Go to Administration -> OAI sets
3) Confirm that the actions 'Modify', 'Delete' and 'Define mappings' have been moved into a drop-down menu and buttons behave as expected.
4) Confirm you are asked to confirm on 'Delete' as per Bug 16014

Sponsored-by: Catalyst IT
Signed-off-by: Nicole C Engard <nengard@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan Gallagher brendan@bywatersolutions.com