Twitter support for iOS5.
 /// <summary>
 /// Posts the image to twitter (when using iOS5).
 /// </summary>
 /// <param name="pictureId">Picture identifier.</param>
 private void PostImageToTwitterIOS5(Guid pictureId)
 {
     var filenameResolver = this.CreateFilenameResolver(pictureId);
     var twitterIOS5 = new TwitterIOS5(this);
     twitterIOS5.PostImage(filenameResolver.MasterImageFilename);
 }