private async Task<WinRtAuthorizer> Authenticate()
 {
     _credentials = await LocalDataCredentials.GetWinRtCredentialsAsync(ApplicationData.Current.LocalFolder);
     if (_credentials.ToString().Equals(",,,,,"))
     {
         _credentials.ConsumerKey = "zPPDxXgf25WedMuVpYpw";
         _credentials.ConsumerSecret = "2Bad9VxQYzfsYDaowidBkoRBIq87wtjjFV8FAvcvV8";
         _credentials.AccessToken = "32533776-uwuq1NLOaJSGdFH3qSrPjHp866I3lssiizrGQowXv";
     }
     _authorizer = new WinRtAuthorizer
     {
         Credentials = _credentials,
         UseCompression = true,
         Callback = new Uri("http://www.twittelytics.com")
     };
     if (!_authorizer.IsAuthorized)
     {
         Task<WinRtAuthorizer> task = _authorizer.AuthorizeAsync();
         await task.ContinueWith(t =>
         {
             _authorizer.ScreenName = _credentials.ScreenName;
             _authorizer.UserId = _credentials.UserId;
         });
         if (_authorizer.IsAuthorized)
         {
             return task.Result;
         }
     }
     return _authorizer;
 }
 public void Logout()
 {
     _credentials.Clear();
     _authorizer = null;
     _credentials = null;
 }