CRM-13444 - ensure all logged mails are marked as completed

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* CRM-13444: Implement UI for setting which writes email output to disk and review implementation for Redirect to DB setting
  http://issues.civicrm.org/jira/browse/CRM-13444
Merge pull request #1737 from dlobo/CRM-13444

CRM-13444 - ensure all logged mails are marked as completed