title: Instantiation of POCO objects with ServiceStack's IAppSettings is not working
body: <p>I have registered <code>AppSettings</code> within my <code>AppHost</code> as shown below:</p>
  
  <pre><code>container.Register&lt;IAppSettings&gt;(new AppSettings());
  </code></pre>
  
  <p>I have added following settings within my <code>web.config</code> file:</p>
  
  <pre><code>&lt;appSettings&gt;
     &lt;add key="baseaddress" value="http://example.com" /&gt;
     &lt;add key="credential" value="{Username:foo,Password:bar}" /&gt;
  &lt;/appSettings&gt;
  </code></pre>
  
  <p>That's my service:</p>
  
  <pre><code>public class ExampleService : Service
  {
      public IAppSettings Settings { get; set; }
  
      public void Post(ExampleRequest request)
      {
          // NOT WORKING -&gt; always NULL!
          var credentials = Settings.Get&lt;Credential&gt;("credential", null);
  
          // OK
          var baseUrl = Settings.GetString("baseaddress");
  
          // more code...
      }
  }
  </code></pre>
  
  <p>This is my <code>Credential</code> class:</p>
  
  <pre><code>public class Credential
  {
      public string Username { get; set; }
  
      public string Password { get; set; }
  }
  </code></pre>
  
  <p>The <code>baseUrl</code> is always set but the <code>credentials</code> variable is always <code>NULL</code> and I don't know why...</p>