frontend connection: only use websockets

fixes issue with order of messages in chrome, and it's better for the
time sync anyway

frontend/src/lib/Connection.ts

@@ -24,7 +24,8 @@ class Connection {
 
     constructor() {
         this.socket = io(this.url, {
-            autoConnect: false
+            autoConnect: false,
+            transports: ['websocket']
         });
 
         this.setupSocketListeners();