Added functionality to automatically select a server

- Added functionality on the DiscoveryServer to return a random server to the player
- Added elements to the UI to support auto-selecting a server
- Added client side code to request a random server

Tags: #story[1281]

src/main/java/seng302/gameServer/messages/ServerRegistrationMessage.java

@@ -17,6 +17,10 @@ public class ServerRegistrationMessage extends Message {
         createMessage(serverName, mapName, address, port, players, capacity, roomCode);
     }
 
+    public static ServerRegistrationMessage getEmptyRegistration() {
+        return new ServerRegistrationMessage("","","",0,0,0,"");
+    }
+
     @Override
     public int getSize() {
         return size;