v2.7.1382

Contest floor ready state

Adds support for issue #1319: a contest floor 'ready event'.

If you add floorReady="true" to the CDS contest configuration, then
/access will report the new state floor_ready property and video feeds
will not be accessible until it is set. There's a new section in the
CDS web admin with a Floor Ready button that sets it to the current
time via a standard patch request.

The team detail (contest floor opening) presentation now checks if
the floor_ready property exists, and displays a message "🚫 Contest
floor is not ready 🚫" if the contest has one. When the property is
set, the message disappears and a chime is played.

We can see how this works in testing, customize it, and bring to the
spec if it's something we want to keep doing.

The one gap: I'm pretty sure that when the CCS outputs a state event
(e.g. when the contest starts) it would reset the property. That
might not be a problem for now, but will have to be addressed at
some point.

Fixes #1319.