added sleep method to JCoBox class that takes a TimeUnit

src/jcobox/JCoBox.java

@@ -104,6 +104,10 @@ public class JCoBox {
 			e.printStackTrace();
 		}
 	}
+	
+	public static void sleep(int duration, TimeUnit unit) {
+	   sleep(unit.toMillis(duration));
+	}
 
 	
 	/**