Bug 19228: Trigger confirm delete when removing item from course

Bug 19228: Trigger confirm delete when removing item from course

To test:
1) Enable UseCourseReserves syspref
2) Go to Course Reserves
3) Add a new course if you don't already have one
4) Add an item to the course
5) Click 'remove' to delete the item from the course
6) Notice the item deletes straight away with no confirmation prompt
7) Apply the patch
8) Repeat steps 4 and 5
9) Confirm the confirmation box pops up and works as expected

Sponsored-by: Catalyst IT
Signed-off-by: Claire Gravely <claire.gravely@bsz-bw.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>