On new sightings, automatically reset visibility to default.

When choosing a rare plant and location combination, the visibility get set
to private. Upon changing the plant or location to a non-rare combination,
the visibility now gets set back to public for a new sighting. (#517)
Rebuild production JS file.
Flag a rare plant sighting for admin. review.

Also reset the approved field upon significant change to a
rare plant sighting. (#517)
Rebuild production JS file.