removed the lazy instantiation from singleton to avoid threading

problems.

singleton/src/main/java/com/iluwatar/IvoryTower.java

@@ -7,14 +7,11 @@
  */
 public class IvoryTower {
 
-	private static IvoryTower instance;
+	private static IvoryTower instance = new IvoryTower();
 
 	private IvoryTower() {}
 
 	public static IvoryTower getInstance() {
-		if(instance ==  null){
-			instance = new IvoryTower();	
-		}
 		return instance;
 	}
 }