title: Web api should return JSon by default
body: <p>This is what I have currently</p>
  
  <pre><code>GlobalConfiguration.Configuration.Formatters.JsonFormatter.MediaTypeMappings.Add(new QueryStringMapping("type", "json", new MediaTypeHeaderValue("application/json")));             
  
  GlobalConfiguration.Configuration.Formatters.XmlFormatter.MediaTypeMappings.Add(new QueryStringMapping("type", "xml", new MediaTypeHeaderValue("application/xml")));
  </code></pre>
  
  <p>it works fine when I call API with query like this </p>
  
  <pre><code>for xml : http://localhost:49533/api/?type=xml
  for json: http://localhost:49533/api/?type=json
  </code></pre>
  
  <p>but what I want is JSON by default? is that possible? I want above options available as well</p>