New option to only allow registered users to speak WIP (#233):

* Prosody mod_muc_peertubelivechat_roles module
* Fix ConverseJS to disable the message field when room is unmoderated
  and user is visitor
* Mute/voice anonymous users when changing room configuration.
* Display a specific message to muted anonymous users.
* Default value for mute_anonymous in channel options.
* Feature documentation

server/lib/configuration/channel/storage.ts

@@ -49,6 +49,9 @@ function getDefaultChannelConfigurationOptions (_options: RegisterServerOptions)
     },
     slowMode: {
       duration: 0
+    },
+    mute: {
+      anonymous: false
     }
   }
 }