Bug 6796: (follow-up) Fix logic for calculating following day's open hours

Bug 6796: (follow-up) Fix logic for calculating following day's open hours

Since days for branch hours are stored as 0-6 in the database, when it's
a Saturday (6) incrementing the date leads to an error when issuing an
hourly loan because no opening hours are found for the non-existent day
(7).

This patch fixes this by calculating the tomorrow day and setting it to
0 if it's greater than 6.

This patch also corrects the mappings for days, where local_day_of_week
caluclates the date with Sunday first, which put it out of sync with the
database opening hours days.

Sponsored-by: Catalyst IT
Sponsored-by: Auckland University of Technology
Signed-off-by: Sam Lau <samalau@gmail.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>