Merge pull request kamranzafar#3 from harbulot/master

Trying to load a classes in the unnamed package causes an exception

Author: kamranzafar

JCL2/src/main/java/org/xeustechnologies/jcl/JarClassLoader.java

@@ -261,7 +261,8 @@ public Class loadClass(String className, boolean resolveIt) {
              * Preserve package name.
              */
             if (result.getPackage() == null) {
-                String packageName = className.substring( 0, className.lastIndexOf( '.' ) );
+                int lastDotIndex = className.lastIndexOf( '.' );
+                String packageName = (lastDotIndex >= 0) ? className.substring( 0, lastDotIndex) : "";
                 definePackage( packageName, null, null, null, null, null, null, null );
             }