properly delegate to sub classes for channels and clients

src/channels/sites/mhsChannel.ts

@@ -5,15 +5,16 @@ import ChannelBase from '../channelBase';
 class MHSChannel extends ChannelBase {
   broadcastMessage(from: ClientBase|MHSClient|null, message: string) {
     for (let client of this.clients) {
-      if (client != from) {
+      if (client != from && client.data.user_type == 'teacher') {
         client.ws.send(message);
         console.log(`sent to ${client.id}: %s`, message);
         console.log(message);
       } else {
-        console.log('client is same as sender');
+        console.log('client is same as sender and/or not a teacher.');
       }
     }
   }
 };
 
+module.exports = MHSChannel;
 export default MHSChannel;