Allow Symfony 3

Author: soullivaneuh

composer.json

@@ -15,11 +15,13 @@
     "require": {
         "php": ">=5.3",
         "sebastian/exporter": "1.*",
-        "symfony/config": "2.*"
+        "symfony/config": "~2.0|~3.0"
     },
     "require-dev": {
         "phpunit/phpunit": ">=3.7"
     },
+    "minimum-stability": "dev",
+    "prefer-stable": true,
     "autoload": {
         "psr-4" : { "Matthias\\SymfonyConfigTest\\" : "" }
     }