Release notes:
* http://symfony.com/blog/symfony-2-5-9-released
* http://symfony.com/blog/symfony-2-5-10-released
* http://symfony.com/blog/symfony-2-5-11-released
Security fix in 2.5.11
* security #14167 CVE-2015-2308 (nicolas-grekas)
* security #14166 CVE-2015-2309 (neclimdul)