public void UpdateImageThumbnail(string partitionKey, string rowKey, string thumbUrl)
{
var results = from g in context.GuestBookEntry
where g.PartitionKey == partitionKey && g.RowKey == rowKey
select g;
var entry = results.FirstOrDefault();
entry.ThumbnailUrl = thumbUrl;
context.UpdateObject(entry);
context.SaveChanges();
}
