Bug 12072: Add system preference for New dateformat dd.mm.yyyy (dmydot)

Bug 12072: Add system preference for New dateformat dd.mm.yyyy (dmydot)

Note: This feature depends on Bug 14870 'Delete C4/Dates from system'

System preferences:
To test:
- apply the patch
- run updatedatabase.pl
- go to Admin > Sysprefs > I18N, change dateformat to dd.mm.yyyy, save
- verify that the value was saved

Date handling:
- go through the staff client and verify that dates behave as expected.
- go through Opac and verify that dates behave as expected.

  The Bugs where Bug 14870 depends on contain test plans that can be
  used for the overall testing.

Note: Make sure that you reset the dateformat to the former value after
      testing.

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Works as expected

Amended to apply on top of Bug 15166 11.11.2015/mv

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>