title: JsonFormatter in WebApi is ignored
body: <p>I need to configure the JSON output of a Web API.</p>
  
  <p>It works, when I directly set the JsonProperty-Attribute on properties.
  But changes in the settings of the JsonFormatter (in the Register-method) are completely ignored.</p>
  
  <pre><code>    public static void Register(HttpConfiguration config)
      {
          // Web API configuration and services   
  
          config.Formatters.JsonFormatter.SerializerSettings.NullValueHandling = NullValueHandling.Ignore;
          config.Formatters.JsonFormatter.SerializerSettings.ContractResolver  = new CamelCasePropertyNamesContractResolver();
  
          // ...
      }
  </code></pre>
  
  <p>What am I doing wrong?</p>