Emit an "error" event only for the case where we have an invalid roomid.
All types of error that might be considered a connection error emit
a "disconnected" event, instead. If there are no listeners for this
event an error will be throw.
Document the "error" and "disconnected" events.
Adjust example to reflect event name change
If there are no listeners for the "disconnected" event, emit an "error"
event instead of throwing an error. Per discussion with @alaingilbert.
Compiled source