* In the bigbluebutton_proxy::action_url call to submodules, we need a way to get
the instance this is called upon so we can have information (parameters) for
this instance settings (like the new settings introduced by subplugins).
* Add the optional instanceid parameter in join/create/getMeetingInfo calls
Display more friendly messages when:
* When displaying activity and the server is not available
* When we join a meeting and the server is not available or an error is detected
Laurent David