fix dependencies on HttpFoundation component

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11636
| License       | MIT
| Doc PR        | 

The ``closeOutputBuffers()`` method was added to the ``Response`` class of the HttpFoundation in Symfony 2.5. Therefore, parts that are calling this method must depend on ``symfony/http-foundation`` 2.5 or higher.
well, until now, we were happy with the indirect dependency. But if we need HttpFoundation 2.5, the right way is to require it explicitly, not to bump another dependency relying on the fact it has also bumped its own dependency