CRM-14367 - Prevent notice by adding display_name to $returnProperties. Also remove unintentionally committed debug line in CRM/Mailing/Form/Settings.php

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* CRM-14367:
  https://issues.civicrm.org/jira/browse/CRM-14367
Merge pull request #3184 from davecivicrm/CRM-14367a

CRM-14367 - Prevent notice by adding display_name to $returnProperties. ...