Bug 10871: Make confirmation message for deleting news translatable

Bug 10871: Make confirmation message for deleting news translatable

To test:
- Create a news entry in tools > news
- Delete the news entry or multiple entries by selecting them
  using the checkboxes to the left and the delete button at the
  bottom of the page.

Verify confirmation message shows up correctly with patch applied.

Bonus:
- Update one of the po files and make sure the new strings shows up
  there.

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit da856fc46cfd4cccb092c339eee0e3ce1262e9d8)
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>