title: How to make Yii2 rest api use json output by default?
body: <p>I've configured rest api like this: 
  <a href="http://www.yiiframework.com/doc-2.0/guide-rest-quick-start.html" rel="nofollow">http://www.yiiframework.com/doc-2.0/guide-rest-quick-start.html</a></p>
  
  <p>How to make Yii2 rest api output json by default instead of XML?</p>