Moderators are able to send a message to the meeting's guest lobby. This new
event reaches bbb-web and is sent to the guest user with her/his status response
while polling. All guest users that are waiting for acceptance will be able to
read this message.
enableGuestLobbyMessage is disabled by default.
Use the former Flash client avatarURL join param to replace the name
initials avatar from the user list, chat, waiting guests and connection
status list.
It is possible to define a defaultAvatarURL at bbb-web and enable/disable it
