prepare release 0.3.0

Author: xabbuh

composer.json

@@ -13,12 +13,12 @@
     ],
     "require": {
         "php": ">=5.3.0",
-        "php-xapi/model": "^0.5.0@dev",
+        "php-xapi/model": "^0.5.0",
         "symfony/serializer": "~2.8|~3.0"
     },
     "require-dev": {
-        "php-xapi/json-test-fixtures": "^0.2.3@dev",
-        "php-xapi/test-fixtures": "^0.5.0@dev",
+        "php-xapi/json-test-fixtures": "^0.2.3",
+        "php-xapi/test-fixtures": "^0.5.0",
         "phpspec/phpspec": "~2.0"
     },
     "conflict": {