extend allowable versions of symfony/event-dispatcher to all future 2.x

composer.json

@@ -13,7 +13,7 @@
     ],
     "require": {
         "php": ">=5.3.2",
-        "symfony/event-dispatcher": ">=2.1.0,<2.3-dev"
+        "symfony/event-dispatcher": "~2.1"
     },
     "autoload": {
         "psr-0": { "Solarium": "library/" }