Various bug fixes

- Fixed bug where an invalid port number would crash the program
- Closed the stage before cleaning up resources. This speeds up closing the app.
- Added error handling for when the client looses connection to the server.

Tags: #story[1281]

src/main/java/seng302/utilities/StreamParser.java

@@ -136,7 +136,6 @@ public class StreamParser {
         long messageLength = bytesToLong(Arrays.copyOfRange(payload, 12, 14));
         String xmlMessage = new String(
             (Arrays.copyOfRange(payload, 14, (int) (14 + messageLength)))).trim();
-        System.out.println(xmlMessage);
         //Create XML document Object
         DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
         DocumentBuilder db;