CRM-13380 : fix status and date filters for mailing search pages

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* CRM-13380: 'Mailings' pages: search doesn't work correctly.
  http://issues.civicrm.org/jira/browse/CRM-13380
CRM-13382 : exposing of 'Canceled', 'All Status' status option of mailing status filter on mailing search pages for easy search

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* CRM-13382: Make 'Mailings' searches more comprehensive
  http://issues.civicrm.org/jira/browse/CRM-13382
* CRM-13380: 'Mailings' pages: search doesn't work correctly.
  http://issues.civicrm.org/jira/browse/CRM-13380
Merge pull request #1636 from pratik-joshi/CRM-13380

CRM-13380 : fix status and date filters for mailing search pages