Update composer.json

Pin-pointed doctrine fixtures to version 2.0

Author: guilhermeblanco

composer.json

@@ -13,7 +13,7 @@
     "require": {
         "php": ">=5.3.2",
         "symfony/framework-bundle": ">=2.0,<3.0-dev",
-        "doctrine/doctrine-fixtures-bundle": "dev-master"
+        "doctrine/doctrine-fixtures-bundle": "2.*"
     },
     "autoload": {
         "psr-0": {