public virtual void DeleteList(string listId)
        {
            var context = new TaskDataContext();

            var list = context.TaskLists
               .Where(t => t.RowKey == listId && t.PartitionKey == listId.Substring(0, 1) && true)
               .SingleOrDefault();

            if (list != null)
            {
                var tasks = context.Tasks
                    .Where(t => t.PartitionKey == listId);

                foreach (TaskRow task in tasks)
                {
                    context.DeleteObject(task);
                }

                context.DeleteObject(list);
                context.SaveChanges();
            }
        }
        public virtual void DeleteTask(string listId, string taskId)
        {
            var context = new TaskDataContext();

            var task = context.Tasks
                .Where(t => t.PartitionKey == listId && t.RowKey == taskId && true)
                .SingleOrDefault();

            if (task != null)
            {
                context.DeleteObject(task);
                context.SaveChanges();
            }
        }