On new job, issue NOTIFY via trigger.

This probably isn't done, as we need to tell people that they have to install
the new trigger function and the trigger if they want NOTIFY's to work
as they did before.

NOTIFY's are no longer issued by the queue_classic gem.
Merge branch 'notify_via_trigger' of git://github.com/joevandyk/queue_classic into joevandyk-notify_via_trigger

Conflicts:
	lib/queue_classic/conn.rb
	lib/queue_classic/queries.rb
	lib/queue_classic/worker.rb
	sql/create_table.sql