Bug 26205: Add logging of news items

Bug 26205: Add logging of news items

To test:

1. Apply patch, updatedatabase, restart_all
2. Make sure the system pref 'NewsLog' is turned on.
3. Go to the Koha News tool and create a new news item.
4. View the logs and display only the OPAC News module
5. You should see your new news, it will include the lang (
   OPACheader_en ) and the content of the news item.
6. Filter the logs so the only action is 'Add', your new news item
   should appear
7. Modify some news items
8. They should appear in the logs now as modification.
9. Make sure you can filter the action to 'Modify' and can confirm it
   works
10. Delete some news items
11. They should appear in the logs now as deletinon
12. Make sure you can filter the action to 'Delete' and can confirm it
    works

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>