Implemented server re-registration when a server closes / updates

- When a server is closed, it will disappear from the server list
- When a player joins a server, the number of spaces left will decrease
- Servers now disappear instead of duplicating
- Added tests for ServerDescription
- Added documentation for new classes

Tags: #story[1247]

src/main/java/seng302/App.java

@@ -7,16 +7,10 @@ import javafx.scene.Parent;
 import javafx.scene.Scene;
 import javafx.scene.image.Image;
 import javafx.stage.Stage;
-import org.apache.commons.cli.CommandLine;
-import org.apache.commons.cli.CommandLineParser;
-import org.apache.commons.cli.DefaultParser;
-import org.apache.commons.cli.Options;
-import org.apache.commons.cli.ParseException;
+import org.apache.commons.cli.*;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import seng302.gameServer.ServerAdvertiser;
-import seng302.model.PolarTable;
-import seng302.visualiser.ServerListener;
 
 import java.io.IOException;
 
@@ -87,6 +81,13 @@ public class App extends Application {
 //            ClientPacketParser.appClose();
 //            ClientPacketParser.appClose();
 
+
+            try {
+                ServerAdvertiser.getInstance().unregister();
+            } catch (IOException e1) {
+                logger.warn("Could not un-register game");
+            }
+
             System.exit(0);
         });