Test lowest version constraints

Author: wouterj

composer.json

@@ -23,10 +23,12 @@
         "symfony-cmf/core-bundle": "~1.1,>=1.1.0"
     },
     "require-dev": {
+        "twig/twig": "~1.12,>=1.12.1",
         "symfony-cmf/routing-bundle": "~1.2,>=1.2.0",
         "symfony-cmf/testing": "~1.2,>=1.2.6",
         "sonata-project/doctrine-phpcr-admin-bundle": "~1.1",
         "sonata-project/block-bundle": ">=2.2.8",
+        "sonata-project/core-bundle": ">=2.2.3",
         "symfony/monolog-bundle": "~2.3"
     },
     "suggest": {