Test components using their lowest possible deps

Author: nicolas-grekas

composer.json

@@ -24,7 +24,8 @@
     },
     "require-dev": {
         "doctrine/collections": "~1.0",
-        "symfony/validator": "~2.3.0",
+        "symfony/validator": "~2.3.0,>=2.3.20",
+        "symfony/translation": "~2.0,>=2.0.5",
         "symfony/http-foundation": "~2.2"
     },
     "suggest": {