title: Xamarin.Auth: Account data not persisted when app is updated
body: <p>I'm using Xamarin.Auth to authenticate with services like foursquare and so. I've gotten my authentication code working all good, the problem is that the account data is not persisted when I deploy a new version of my app - each time I deploy a test version on the phone, I've to re-authenticate.</p>
  
  <p>Here's how I store the account;</p>
  
  <pre><code>  /// &lt;summary&gt;
  /// Stores the account.
  /// &lt;/summary&gt;
  private void StoreAccount(AuthenticatorCompletedEventArgs eventArgs)
  {
      if (!eventArgs.IsAuthenticated) // make sure we are authenticated.
      {
          Log.Debug(Logging.AppTag, "FourSquareClient can't store account as auth. is cancelled. ");
          return;
      }
  
      this.IsAuthenticated = true;
      this.Account = eventArgs.Account;
  
      AccountStore.Create(this.OwnerContext).Save(eventArgs.Account, "Foursquare");
  }
  </code></pre>
  
  <p>and here is how I check if we have a stored account;</p>
  
  <pre><code> /// &lt;summary&gt;
  /// Retrieves stored account.
  /// &lt;/summary&gt;
  private void RetrieveAccount()
  {
      if (this.IsAuthenticated)
      {
          Log.Debug(Logging.AppTag, "FourSquareClient is already authenticated! ");
          return;
      }
  
  
      var accounts = AccountStore.Create(this.OwnerContext).FindAccountsForService("Foursquare");
      var enumerable = accounts as IList&lt;Account&gt; ?? accounts.ToList();
  
      if (enumerable.Any())
      {
          Log.Info(Logging.AppTag, "Foursquareclient found account data.");
          this.IsAuthenticated = true;
          this.Account = enumerable.First();
      }
      else
      {
          Log.Info(Logging.AppTag, "Foursquareclient no account data found!");
          this.IsAuthenticated = false;
          this.Account = null;
      }
  }
  </code></pre>