fix dependencies on HttpFoundation component

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.
bug #11637 fix dependencies on HttpFoundation component (xabbuh)

This PR was merged into the 2.5 branch.

Discussion
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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.

Commits
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fe2f007 fix dependencies on HttpFoundation component