Hypercast browser extension v0.0.9

New clients will sync automatically to the current playback state when
joining a session. This improvement required a breaking change to the
protocol, so all clients must upgrade to 0.0.9 to communicate.

Some bugs introduced in 0.0.8 where playback would fail to sync to
other clients have been fixed.

Client ID configuration has been removed from settings since setting
your client ID never had any effect. Setting a display name will be
added in a future release, but it would not have any effect now
because there is nowhere in the interface for a display name to be
displayed.