* FIX: Clear stale status of reloaded reviewables
Navigating away from and back to the reviewables reloaded Reviewable
records, but did not clear the "stale" attribute.
* FEATURE: Show user who last acted on reviewable
When a user acts on a reviewable, all other clients are notified and a
generic "reviewable was resolved by someone" notice was shown instead of
the buttons. There is no need to keep secret the username of the acting
user.