Bug 5944 : (MT #3000) new cronjob script to delete old suggestions

Bug 5944 : (MT #3000) new cronjob script to delete old suggestions

This patch is a new script that delete suggestion that have be processed by librarians.
It take on argument, it's a number of days to keep suggestions. Suggestions olders than TODAY - $days will be deleted.
This script should be used to purge suggestions and clean the table in intranet.

Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>