Fix FileResource test

I had the following test failing on OS X before:

There was 1 failure:

1) Symfony\Component\Config\Tests\Resource\FileResourceTest::testSerializeUnserialize
Failed asserting that two strings are identical.
Merge branch '2.2' into 2.3

* 2.2:
  [FrameworkBundle][Security] Replaced void return type with null for consistency
  fixed CS
  NativeSessionStorage regenerate
  removed unneeded comment
  Use setTimeZone if this method exists.
  Fix FileResource test
  fixed wrong usage of unset()
  [HttpFoundation] Fixed the way path to directory is trimmed.
  [Console] Fixed argument parsing when a single dash is passed.

Conflicts:
	src/Symfony/Component/HttpKernel/Debug/ErrorHandler.php