CRM-13085 - Add CRM_Core_TransactionTest

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* CRM-13085: Transaction rollback doesn't work with contact creation (due to ACL TRUNCATE)
  http://issues.civicrm.org/jira/browse/CRM-13085
CRM-13085 - Fix premature transaction commit stemming from TRUNCATE TABLE civicrm_acl_contact_cache

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* CRM-13085: Transaction rollback doesn't work with contact creation (due to ACL TRUNCATE)
  http://issues.civicrm.org/jira/browse/CRM-13085
Merge pull request #1199 from totten/master-premature-commit

CRM-13085 - Fix premature transaction commit (due to ACL)