Bug 13858: Datatables paging on Koha news tool page slightly broken

Bug 13858: Datatables paging on Koha news tool page slightly broken

The paging is slightly broken in the datatables table on the
news page in the tools module.

To test:
- Access the tools > news page
- Make sure you have a few news entries
- Check that the paging is broken without the patch and
  fixed once the patch is applied

Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>
(cherry picked from commit f3e02d2496a411b52304b4ade8b9594442993020)
Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>