Bug 8337 System preferences for longoverdue cron

Bug 8337 System preferences for longoverdue cron

Patch to follow that adds 3 new system preferences to control the
parameters for the longoverdue script.
New prefs are DefaultLongOverdueChargeValue, DefaultLongOverdueLostValue
and DefaultLongOverdueDays.
These preferences are used when you call the longoverdue.pl script without
their parameters.

Sponsored-By: CCSR
Signed-off-by: Leila and Fridos help <koha.aixmarseille@gmail.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>