Bug 26844: Add warning to disabled logs on log viewer

Bug 26844: Add warning to disabled logs on log viewer

To test:
1 - Go to Admin->System preferences->Logs tab
2 - Make sure some logs are disabled
3 - Go to Tools->Log viewer
4 - Note you can select logs that are disabled
5 - Apply patch
6 - Reload page
7 - Note disabled logs have a warning icon and hover text

Signed-off-by: Séverine QUEUNE <severine.queune@bulac.fr>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>