update models + added social network account services

lib/User/Helper/GravatarHelper.php

@@ -0,0 +1,15 @@
+<?php
+namespace Da\User\Helper;
+
+class GravatarHelper
+{
+    public function buildId($email)
+    {
+        return md5(strtolower(trim($email)));
+    }
+
+    public function getUrl($id, $size = 200)
+    {
+        return '//gravatar.com/avatar/' . $id . '?s=' . $size;
+    }
+}