The substr string method is receiving the wrong type of parameter
as length (boolean instead of number) forcing it to always use the
english fallback.

This introduces initial translations for the guest-wait pages.
The only supported languages are en and de for now. Needs a concept
to hook it up with transifex.

Included a message and a redirect for the cases where the guest is
not allowed to join or the meeting has expired/ended.

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.

fixed typo