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

lib/PayPal/Common/ArrayUtil.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace PayPal\Common;
+
+/**
+ * Class ArrayUtil
+ * Util Class for Arrays
+ *
+ * @package PayPal\Common
+ */
+class ArrayUtil
+{
+
+    /**
+     *
+     * @param array $arr
+     * @return true if $arr is an associative array
+     */
+    public static function isAssocArray(array $arr)
+    {
+        foreach ($arr as $k => $v) {
+            if (is_int($k)) {
+                return false;
+            }
+        }
+        return true;
+    }
+}