Add firehose subscription to Trac Notifications page

[ericlewis]

Currently, the trac "firehose" requires subscription to a ​separate mailing list. We should integrate this into the ​user notification settings page. Although the fact that it isn't there already leads me to think there's a technical hurtle here.

The mailing list is somewhat more efficient than the notifications code. It's not that it couldn't be done, but it would kind of be reinventing the wheel, and also making it more pentagonal. :)

This ticket was mentioned in IRC in #wordpress-meta by sams. ​View the logs.