CRM_Core_DAO::createTestObject - Handle dates and timestamps differently

With the old code, api_v3_ACLPermissionTest (when called as part of
api_v3_AllTests) passes on my local MAMP install but fails on Debian and
Ubuntu.
Merge pull request #2809 from totten/doctrine-test-fixes

CRM_Core_DAO::createTestObject - Handle dates and timestamps differently