title: instaSharp oauthResponse Not work
body: <p>I want to use instaSharp to use instagram api , get followers anp posts and ... 
  when I get code with callbackUrl I cant Send Requesttoken(code) 
  and my oauthResponse is null ...
  this is my code : </p>
  
  <pre><code>async Task getaouth()
      {
          var clientId = ConfigurationManager.AppSettings["client_id"];
          var clientSecret = ConfigurationManager.AppSettings["client_secret"];
          var redirectUri = ConfigurationManager.AppSettings["redirect_uri"];
          var realtimeUri = "";
  
          InstagramConfig config = new InstagramConfig(clientId, clientSecret, redirectUri, realtimeUri);
  
          Session.Add("InstaSharp.config", config);
  
  
          // add this code to the auth object
          var auth = new InstaSharp.OAuth(config);
  
          // now we have to call back to instagram and include the code they gave us
          // along with our client secret
          var oauthResponse = await auth.RequestToken(code);
  
          // tell the session that we are authenticated
          //config.isAuthenticated = true;
  
  
  
  
          Response.Write(r.ToString());
  
          // both the client secret and the token are considered sensitive data, so we won't be
          // sending them back to the browser. we'll only store them temporarily.  If a user's session times
          // out, they will have to click on the authenticate button again - sorry bout yer luck.
          Session.Add("InstaSharp.AuthInfo", oauthResponse);
  
          // all done, lets redirect to the home controller which will send some intial data to the app
          //return RedirectToAction("Index", "Home");
          Response.Write("");
      }
  </code></pre>
  
  <p>after this my oauthResponse is null !
  and after call this method 
  _users.GetSelf()
  i get it : 
  <strong>An exception of type 'System.InvalidOperationException' occurred in        InstaSharp.dll but was not handled in user code
  Additional information: You are not authenticated</strong></p>