title: Could not find implicit Marshaller in Spray.io when using Jackson
body: <p>I have a Spray.io directive that handles a POST and I want to use Jerkson (scala interface for Jackson) to parse the incoming JSON into the appropriate class.</p>
  
  <pre><code>post {
          path("") {
            entity(as[String]) { stuff =&gt;
                complete {
                  parse[User](stuff)
                }
            }
          }
        }
  </code></pre>
  
  <p>The issue is that when I go to compile, Spray goes looking for a Marshaller:</p>
  
  <pre><code>    [error] C:\project\src\main\scala\com\project\AccountService\controllers\Users.scala:53: 
  could not find implicit value for evidence parameter of type
   spray.httpx.marshalling.Marshaller[com.project.AccountService.models.User]
      [error]                     parse[User](stuff)
      [error]                                ^
      [error] one error found
  </code></pre>
  
  <p>Do I need to write a custom Marhsaller for this? Or is my directive not written properly? And if I do need one, any good examples out there?</p>
  
  <p>Thanks!</p>