Remove executable bit on ContainerAwareTrait PHP file

File [`src/Symfony/Component/DependencyInjection/ContainerAwareTrait.php`](https://github.com/symfony/symfony/blob/master/src/Symfony/Component/DependencyInjection/ContainerAwareTrait.php) is executable, while it should not.

![image](https://f.cloud.github.com/assets/99944/1572646/b9c7f996-5121-11e3-8c86-80bfc91039dd.png)