Replacing deprecated security context

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.6+
| Fixed tickets | #4511 

This PR turned out larger than wanted. I wasn't able to test all changes, but as stated in http://symfony.com/blog/new-in-symfony-2-6-security-component-improvements replacing should work without problems.
That's weird, when I check this in my current branch, I can't find it... Let mee see if a push fixes this

```php
    private $tokenStorage;

    public function __construct(TokenStorageInterface $tokenStorage)
    {
        $this->tokenStorage = $tokenStorage;
    }
```