Fixed RoomCont... to return specific device data

@tommi27 why are you not avaliable at 1am?

src/main/java/ch/usi/inf/sa4/sanmarinoes/smarthut/controller/RoomController.java

@@ -79,7 +79,7 @@ public class RoomController {
      * id).
      */
     @GetMapping(path = "/{roomId}/devices")
-    public @ResponseBody List<? extends Device> getDevices(@PathVariable("roomId") long roomid) {
+    public List<Device> getDevices(@PathVariable("roomId") long roomid) {
         return deviceRepository.findByRoomId(roomid);
     }
 }