Backport: email cloaking does not work with & in text to 2.5.x

Please see the orginal issue for 3.x (#4263) and the PR (#4273)

The same issue is in 2.5.x and the same fix work good for me.

Sinze the code is not from me i mark the first successful test.

libraries/joomla/html/html/email.php

@@ -102,13 +102,17 @@ public static function cloak($mail, $mailto = true, $text = '', $email = true)
 	 */
 	protected static function _convertEncoding($text)
 	{
+		$text = html_entity_decode($text);
+
 		// Replace vowels with character encoding
 		$text = str_replace('a', 'a', $text);
 		$text = str_replace('e', 'e', $text);
 		$text = str_replace('i', 'i', $text);
 		$text = str_replace('o', 'o', $text);
 		$text = str_replace('u', 'u', $text);
 
+		$text = htmlentities($text,ENT_QUOTES,'UTF-8',false);
+
 		return $text;
 	}
 }