Forgot to add compat interface

compat/JsonSerializable.php

@@ -0,0 +1,13 @@
+<?php
+
+/**
+  * This interface exists to provide backwards compatibility with PHP 5.3
+  */
+interface JsonSerializable
+{
+    /**
+     * Returns data that can be serialized by json_encode
+     *
+     */
+    public function jsonSerialize();
+}