title: Add another object into existing JSON
body: <p>I'm not sure I'm asking this exactly right, but here's the situation.</p>
  
  <p>I have an existing JSON object like this and I need to "inject" a new object into this where indicated:</p>
  
  <pre><code>{
      "version": "1.0.0",
      "stat_tag": "API",
      "layers": [{
              "type": "cartodb",
              "options": {
                  "sql": "SELECT * FROM mytable)",
                  "cartocss": "mytable{marker-width: 10;}",
                  "cartocss_version": "2.1.0"
              }
          }
          //INSERT NEW OBJECT HERE
      ]
  }
  </code></pre>
  
  <p>The object I need to inject is stored as a variable, I just don't know how to push it into the existing object in the right place.</p>