1.0.3dev: Notifications when ticket attachments are added or deleted. Refs #2259.

Notifications are controlled by the option `[notification]` `ticket_notify_attachment`. The default value of the option is `True`.


git-svn-id: http://trac.edgewall.org/intertrac/log:/branches/1.0-stable@13380 af82e41b-90c4-0310-8c96-b1721e28e2e2