Bug 19806: Add classes to itemnotes in issues table

Bug 19806: Add classes to itemnotes in issues table

To test:
1 - Checkout an item with both public and non-public notes
2 - Note the notes display and both have circ-hlt class
3 - Apply patch
4 - Ensure display has not changed
5 - Note notes now have classes 'item-note-public' and
'item-note-nonpublic'
6 - Sign off

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>