Bug 15839: Koha::Reviews - Add Koha::Review[s] classes

Bug 15839: Koha::Reviews - Add Koha::Review[s] classes

The subroutines in C4::Reviews are only doing CRUD operations.
This patch set moves them to 2 new Koha::Review[s] classes.

Test plan for the whole patch set:
0/ Set the reviewson syspref
1/ At the OPAC, create a couple of reviews for a record
Try and create a review without html tags different that br b i em big
small strong: You should get a warning.
2/ Edit a review
3/ On the Staff interface, you should see a "Comments pending approval"
link on the mainpage
4/ Approve 1 review and delete the other
5/ At the OPAC you should only see 1 review (the approved one) in the
"Comments" tab
6/ Modify the review
7/ The review should appear again in the "comments awaiting moderation"
tab.
Note that even the comment has not been changed, it will have to be
reapproved (FIXME later). This behavior already existed prior to this
patch.

Tested all patches together (with database updated)
Signed-off-by: Marc Veron <veron@veron.ch>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>