updated VERSION for 2.3.13
bumped Symfony version to 2.3.14
Added test when TTL has expired
[HttpKernel] fixed default TTL not applied under certain conditions
Merge branch '2.3' into 2.4

* 2.3:
  Disable 5.6 until it is stable again.
  Update the fixtures.
  [HttpKernel] fixed default TTL not applied under certain conditions
  Added test when TTL has expired