[Console] fixed input bug when the value of an option is empty (closes #6649, closes #6689)
Merge branch '2.0' into 2.1

* 2.0:
  [Yaml] fixed default value
  Added Yaml\Dumper::setIndentation() method to allow a custom indentation level of nested nodes.
  added a way to enable/disable object support when parsing/dumping
  added a way to enable/disable PHP support when parsing a YAML input via Yaml::parse()
  [Console] fixed input bug when the value of an option is empty (closes #6649, closes #6689)

Conflicts:
	src/Symfony/Component/Yaml/Dumper.php
	src/Symfony/Component/Yaml/Parser.php
	src/Symfony/Component/Yaml/Tests/DumperTest.php
	src/Symfony/Component/Yaml/Tests/ParserTest.php
	src/Symfony/Component/Yaml/Yaml.php