fixing php 5.3 compatibility
PHP Fatal error: Can't inherit abstract function OCP\ISession::set() (previously declared abstract in OC\Session\Session)
php 5.3 compatibility for \OC\Files\Storage
php 5.3 compatibility for Test_Files_Sharing_Api
php 5.3 compatibility for \OC\AppFramework\DependencyInjection\DIContainer
Merge pull request #5221 from owncloud/fixing-5217-master

fixing php 5.3 compatibility