Set cost type to integer

This seems to be a remnant of when the code dealt with crypt() directly. The password_hash() function expects the cost option to be an LVAL (it does a type conversion for strings).
Merge branch '2.3'

* 2.3:
  bumped Symfony version to 2.3.6
  updated VERSION for 2.3.5
  updated CHANGELOG for 2.3.5
  Set cost type to integer
  bumped Symfony version to 2.2.9
  updated VERSION for 2.2.8
  updated CHANGELOG for 2.2.8
  bumped the version
  fixed typo
  updated VERSION for 2.2.7
  update CONTRIBUTORS for 2.2.7
  updated CHANGELOG for 2.2.7
  bugix: CookieJar returns cookies with domain "domain.com" for domain "foodomain.com"
  fixed HTML5 form attribute handling XPath query
  Removed old way of building icu data.

Conflicts:
	src/Symfony/Component/HttpKernel/Kernel.php