pgAgent wishlist

1. Be able to LISTEN to notifications from a Postgres database, and run a job depending on which notification is fired
2. Allow send email after job finishes, configurable to send only on error. You don't need to make your own MTA, just drop a message in localhost:25
3. A yum package
4. Use RFC 5545 RRULES, as it's the standard for scheduling
5. Fix the bug that shows failure when a Windows batch file returns success