Run security:check command for Symfony >= 2.6 projects

[smatyas]

It would be nice to (optionally?) run the security check command for Symfony projects (>= 2.6).
http://symfony.com/blog/new-in-symfony-2-6-the-security-check-command

[nullziu]

I think it's a great feature, and we should definitely consider to add it to ndeploy as an optional task.

UPDATE:
I also ran into this: https://github.com/sensiolabs/security-checker