title: Serialize only Date part of DateTime in web api 2
body: <p>Having this object :</p>
  
  <pre><code>public class Person {
      public string FirstName { get; set; }
      [DataType(DataType.Date)]
      public DateTime Birthday { get; set; }
  }
  </code></pre>
  
  <p>Returning this object as content in Web Api 2 generates this json for Birthday : </p>
  
  <p><code>"2014-02-20T17:00:32.7114097+00:00"</code> </p>
  
  <p>How can I make it to be : <code>"2014-02-20"</code> without the time part?</p>