* Change table name from ost_email_filter* to ost_filter*
* Add patch for target field.

But don't send out canned responses for new tickets that matched a filter
with an attached canned response if that response is not enabled. Also,
explicitly block deletes to filters that are in use.

And fix various lint issues, include adding the yet-undefined-but-referenced
deleteAttachment() function for canned-responses and faq entries

Also add a cron job to perform the task on demand
Change the implementation for Ticket::deleteAttachments to call this method
after simply removing all entries from the %ticket_attachment table