Bug 15932: Moving Authorities actions into a drop-down menu

 Bug 15932: Moving Authorities actions into a drop-down menu

Edit: Removed datatables stuff and fixed merge conflict
Edit: Removed code from Comment 9 (no it wasn't intentional)
Edit: Putting <tr> line back

To test:
1) Go to Authorities and do an authority search (authorities-home.pl)
2) Confirm that the options (Edit, Merge, Delete) are there and behave
   as expected.
EDIT: 3) Click Delete then Cancel, confirm page does not scroll to the top

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