title: Play Framework 2.1 - Cannot find an implicit ExecutionContext
body: <p>I am calling a webservice like this:</p>
  
  <pre><code>WS
    .url(url)
    .get
    .map { response =&gt; // error occurs on this line
      response.status match {
        case 200 =&gt; Right(response.json)
        case status =&gt; Left(s"Problem accessing api, status '$status'")
    }
  }
  </code></pre>
  
  <p>The complete error: <code>Error: Cannot find an implicit ExecutionContext, either require one yourself or import ExecutionContext.Implicits.global</code></p>