Remove unused checkJava from demo

extensions/demos/html/checkJava.java

@@ -1,25 +0,0 @@
-/*
- * Copyright (c) 2006-2019 Wade Alcorn - wade@bindshell.net
- * Browser Exploitation Framework (BeEF) - http://beefproject.com
- * See the file 'doc/COPYING' for copying permission
- */
-
-import java.io.*;  
-import java.util.*;
-import java.net.*;
-import java.applet.*;
-
-// Keith Lee
-// Twitter: @keith55
-// http://milo2012.wordpress.com
-// keith.lee2012[at]gmail.com
-
-public class checkJava extends Applet{  
- 	public static int results = 0;
-	public void init() {
-	}
-        public int getInfo() {
-		results = 1;
-		return results;
-	}
-}