Update composer.json, BC with the metadata library

composer.json

@@ -12,7 +12,7 @@
     ],
     "require": {
         "php": ">=5.3.2",
-        "metadata/metadata": ">=1.1.0"
+        "jms/metadata": ">=1.1.0"
     },
     "suggest": {
         "symfony/framework-bundle": "2.*"