Bug 25418: (bug 25133 follow-up) Display due date with hours

Bug 25418: (bug 25133 follow-up) Display due date with hours

And not as due date, it's not a display-only info, but an input.

This patch is a follow-up of Bug 25133: Fix time part of due date for 12hr

== Test plan ==
1. create checkouts with the following params and results
2. tomorrow 11:59 PM timeformat syspref: 12h
   - item is due without a specific time, only date (after-checkout green box)
3. backdate 11:59 PM timeformat syspref: 12h
   - note the yellow confirm box has only the date
   - item is due at 12:00 PM (after-checkout green box)
4. tomorrow 11:23 AM timeformat syspref: 12h
   - item is due at 11:23 AM (after-checkout green box)
5. backdate 11:23 AM timeformat syspref: 12h
   - note the yellow confirm box has the date and time
   - item is due 11:23 AM (after-checkout green box)
6. tomorrow 23:59 timeformat syspref: 24h
   - item is due without a specific time, only date (after-checkout green box)
7. backdate 23:59 timeformat syspref: 24h
   - note the yellow confirm box has only the date
   - item is due at 00:00 (after-checkout green box)
8. tomorrow 11:23 timeformat syspref: 24h
   - item is due at 11:23 (after-checkout green box)
9. backdate 11:23 timeformat syspref: 24h
   - note the yellow confirm box has the date and time
   - item is due 11:23 (after-checkout green box)
10. apply patch
11. create checkouts with the following params and results
12. tomorrow 11:59 PM timeformat syspref: 12h
    - item is due without a specific time, only date (after-checkout green box)
13. backdate 11:59 PM timeformat syspref: 12h
    - note the yellow confirm box has the date and time
      - CHANGE COMPARED TO BEFORE THE PATCH
    - item is due without a specific time, only date (after-checkout green box)
      - CHANGE COMPARED TO BEFORE THE PATCH
14. tomorrow 11:23 AM timeformat syspref: 12h
    - item is due 11:23 AM (after-checkout green box)
15. backdate 11:23 AM timeformat syspref: 12h
    - note the yellow confirm box has the date and time
    - item is due 11:23 AM (after-checkout green box)
16. tomorrow 23:59 timeformat syspref: 24h
    - item is due without a specific time, only date (after-checkout green box)
17. backdate 23:59 timeformat syspref: 24h
    - note the yellow confirm box has the date and time
      - CHANGE COMPARED TO BEFORE THE PATCH
    - item is due without a specific time, only date (after-checkout green box)
      - CHANGE COMPARED TO BEFORE THE PATCH
18. tomorrow 11:23 timeformat syspref: 24h
    - item is due at 11:23 (after-checkout green box)
19. backdate 11:23 timeformat syspref: 24h
    - note the yellow confirm box has the date and time
    - item is due 11:23 (after-checkout green box)

Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>