Both debounce or throttle could be used to prevent a spammer from
annoying the moderators.
With debounce, a spammer won't even be noticed by the mods, but
there won't be new notifications for legit guests during the spam.
With throttle, a spammer could still annoy the mods, we would only make
the interval between notifications bigger.
It is a tradeoff. An ideal solution would be preventing spamming from
the same user, but probably unnecessarily complex.
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
