Revert "Event.chronological.  #2820."

This reverts commits 8d93b3424e1db6f147e9fc4bf6d3b355dd1d1363,
bf23aa8625d9f05374173e52af526dc8286a7311, and
eb9260210b38156ea740b648b312f8da2dbf8b03.

Event.chronological currently returns read-only records (probably due to
its use of .joins).  This unfortunately won't fly.

Conflicts:
	config/initializers/paper_trail.rb