Reset store state when logging out

This prevents leaking of state that we do not want to share with the next user

src/stores/RoomViewStore.js

@@ -73,6 +73,9 @@ class RoomViewStore extends Store {
             case 'join_room':
                 this._joinRoom(payload);
                 break;
+            case 'on_logged_out':
+                this.reset();
+                break;
         }
     }