Fixed a minor type for the MBTA RSS link.
createPayload function was accidentally commented out,
which caused MBTA event creation to fail.  Yow.

New model, EventLog.
Altered event "view" view and event_detail template to show log messages.

RSS title link now points to the gracedb query page.
Maybe not right, but better than the broken link that was there.

Changed uid to graceid, since it's not a uid.
Requires database change:
    ALTER TABLE gracedb_event DROP INDEX uid