Fixes hash creation for Gravatar view helper - Closes #398

See also: https://en.gravatar.com/site/implement/hash/

library/Zend/View/Helper/Gravatar.php

@@ -310,7 +310,7 @@ class Zend_View_Helper_Gravatar extends Zend_View_Helper_HtmlElement
     {
         $src = $this->_getGravatarUrl()
              . '/'
-             . md5($this->getEmail())
+             . md5(strtolower(trim($this->getEmail())))
              . '?s='
              . $this->getImgSize()
              . '&d='