[DomCrawler] lowered parsed protocol string (fixes #6986)
Merge branch '2.0' into 2.1

* 2.0:
  [Form] Fixed "label" option to accept the value "0"
  [DomCrawler] lowered parsed protocol string (fixes #6986)

Conflicts:
	src/Symfony/Component/Form/Extension/Core/Type/FieldType.php
	tests/Symfony/Tests/Component/Form/Extension/Core/Type/FieldTypeTest.php