Bug 16907: Koha::Patrons - Move DelMember to ->delete

Bug 16907: Koha::Patrons - Move DelMember to ->delete

This patch moves the C4::Members::DelMember subroutine to the
Koha::Patron module.
The delete method must be overwritten to permit handling of patron's
holds.

Test plan:
(With the 2 patches applied)
1/ Create a patron with holds and owner of lists
2/ Delete patrons using the web interface:
 - More > Delete on a patron page
 - Batch patron deletion tools
3/ and the cronjob script
 - perl misc/cronjobs/delete_patrons.pl -c [more options]

The patron should have been moved to the deletedborrowers table, his/her
holds and lists should have been deleted.

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>