Merge branch '2.8' into 3.1

* 2.8:
  fixed composer.json
  [Config] fix dev dependencies

Author: fabpot

src/Symfony/Component/Config/composer.json

@@ -19,6 +19,9 @@
         "php": ">=5.5.9",
         "symfony/filesystem": "~2.8|~3.0"
     },
+    "require-dev": {
+        "symfony/yaml": "~2.7|~3.0.0"
+    },
     "suggest": {
         "symfony/yaml": "To use the yaml reference dumper"
     },