Bug 13881: Add desk management

Bug 13881: Add desk management

Add a desk and linked it to a library (branch). That's it. In the
future it'll have super features like being able to link waiting
reserve to a specific desk.

Test plan:

1. go to the administration page and notice there isn't any mention of
desk whatsoever
2. apply patches
3. ./installer/data/mysql/updatedatabase.pl
4. prove t/db_dependent/Koha/Desks.t
5. you now have desks links in admin-home and admin-menu
6. click the link
7. add a desk
8. add another one
9. delete one
10. you should have a fair list of all current desks defined
11. Done

Signed-off-by: Séverine QUEUNE <severine.queune@bulac.fr>
Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>