updated symfony/yaml
final version 3.1.0
Merge branch 'redaxo4/master'

Conflicts:
	vendor/autoload.php
	vendor/composer/ClassLoader.php
	vendor/composer/autoload_classmap.php
	vendor/composer/autoload_real.php
	vendor/symfony/yaml/Symfony/Component/Yaml/Parser.php
	vendor/symfony/yaml/Symfony/Component/Yaml/Yaml.php
	vendor/symfony/yaml/Symfony/Component/Yaml/composer.json