Users are often puzzled why there are short recordings. Previously
the only way to see this was to examine Moonfire's logs. This should
be a much better experience to find it right in the UI where you're
wondering, and without the potential the logs are gone.
Fixes#302
This gives much better information to the UI layer, getting rid of a
whole troubleshooting guide entry. See #119#132#218#219
I also restructured the code in anticipation of a new WebSocket event
stream (#40).
