Made two of the regular expressions compatible with PHP 5.5+

The /e modifier was deprecated in PHP 5.5 and it is recommended to use preg_replace_callback instead. I found two (hopefully the only two) instances of the /e modifier being used in the security class and replaced them with preg_replace_callback() versions. This change will continue to work in PHP 5.3 as there is nothing new about how preg_replace_callback() is being used.