Test lowest versions of dependencies
Merge remote-tracking branch 'symfony/2.5' into lowest-26

* symfony/2.5:
  Test lowest versions of dependencies
  Test components using their lowest possible deps

Conflicts:
	src/Symfony/Bridge/Twig/composer.json
	src/Symfony/Bundle/FrameworkBundle/composer.json
	src/Symfony/Bundle/SecurityBundle/composer.json
	src/Symfony/Component/EventDispatcher/composer.json
	src/Symfony/Component/HttpKernel/composer.json
	src/Symfony/Component/Security/composer.json
[2.6] Test lowest versions of dependencies