title: Retrofit parse a json with dynamic keys
body: <p>I want to use retrofit for my webservices.
  I am getting a problem how can I define an object with dynamic Keys.
  I am trying to get data for today and tomorrow. Dates will always change.</p>
  
  <p>Here is the json:</p>
  
  <pre><code>{ "2015-11-13": [  ], "2015-11-14": [  ]}
  </code></pre>