We now write the fact that a message was created or updated to a log
table and actually update the tsvector asynchronously from a worker
process.
This also means that when running locally, one now needs to run the
process_fts_updates script in order to have new messages indexed for
full text search.
(imported from commit ebb11b08d30be2a45242dafe146e8e861a0f050a)
Zev Benjamin