Renaming Namespaces and Organizing Classes

- Updated OpenId classes to be in API namespace
- Updated PP Naming Convention to PayPal Naming Convention
- FormatConverter Class got its own namespace
- Handlers are grouped in Handler namespace
- Samples and Tests Updated Accordingly

tests/PayPal/Test/Validation/NumericValidatorTest.php

@@ -1,7 +1,7 @@
 <?php
 namespace PayPal\Test\Validation;
 
-use PayPal\Common\FormatConverter;
+use PayPal\Converter\FormatConverter;
 use PayPal\Validation\NumericValidator;
 
 class NumericValidatorTest extends \PHPUnit_Framework_TestCase