install yii2 dev dependency

Author: plumthedev

composer.json

@@ -1,10 +1,13 @@
 {
   "name": "plumthedev/yii2-php-cs-fixer-config",
+  "version": "1.0.1",
   "description": "Yii2 PHP coding standards configuration",
   "type": "library",
   "require": {
     "friendsofphp/php-cs-fixer": "^2.16",
-    "yiisoft/yii2": "~2.0.0"
+    "yiisoft/yii2": "~2.0.0",
+    "yiisoft/yii2-dev": "^2.0",
+    "ext-json": "*"
   },
   "require-dev": {
     "phpunit/phpunit": "4.3.*"