Use absolute times for timestamps older than a day.

"2 days ago" repeated twenty times isn't super helpful.
Rename border image to blow away caching.
Style visitor count to look more natural in status bar.
Rework permissions for closed events.

Mutating existing content should still be possible after closing an
event, we just don't want new updates to be posted. Instead of checking
for the event state in validators, instead we check event state at
permission generation time and revoke "update" permissions in that case.