CRM-14446 contact.get api tests + fix on date filters

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* CRM-14446: Contact.get api - birth_date & deceased_date fixes
  https://issues.civicrm.org/jira/browse/CRM-14446
CRM-14446 contact api.getfields declare birth_date & deceased_date high low filters so they will accept strtotime strings

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* CRM-14446:
  https://issues.civicrm.org/jira/browse/CRM-14446
Merge pull request #2860 from eileenmcnaughton/CRM-14446

CRM-14446 contact.get api tests + fix on date filters