In current behavior, accounts are only updated (via UpdateTime call on scheduler) when:
 - refresh cronjob runs, 1x per minute
 - AssignTasks is called

This means we fail to account for completion of tasks, if the task completion notification comes a bit earlier than the AssignTasks notification.

This can be easily remedied by:
 1) in reconciler.Notify: sort incoming notifications chronologically (if more than 1)
 2) call UpdateTime with the notification time, prior to applying the notification.