title: Passing GET parameter to a weird URL pattern (RetroFit 1.9)
body: <p>Please excuse the title; I was not sure how to describe this problem:</p>
  
  <p>I have a REST service URL that looks like:</p>
  
  <pre><code>@GET("/ProfileData/CustomerDetails('1234')?$format=json")
  CustomerDetailsResponse getContactDetails();
  </code></pre>
  
  <p>Here, "1234" is the ID for the customer and I need to pass this in getContactDetails(). </p>
  
  <p>How would I go about this with RetroFit 1.9? (can't update to 2.0 just yet).</p>