SQL patch for notification

Summary: Added PhabricatorBuiltinPatchList entry so that "storage upgrade" will update the database. Renamed and numbered the notification.sql patch.

Test Plan: Drop phabricator_feed.feed_storynotification table if it exists and run bin/storage upgrade to check if the patch is correctly applied.

Reviewers: epriestley, btrahan, allenjohnashton

Reviewed By: epriestley

CC: ddfisher, aran, Korvin

Differential Revision: https://secure.phabricator.com/D2687