title: RoutePrefixAttribute in ASP.NET 5
body: <p>I've started a new Web API 2.0 project in ASP.NET 5. I try to create custom RoutePrefixAttribute class but I get this error </p>
  
  <pre><code>The type or namespace name 'RoutePrefixAttribute' could not be found 
  (are you missing a using directive or an assembly reference?)   {ProjectName}.DNX Core 5.0
  </code></pre>
  
  <p>Should I use some other class instead? </p>