CRM-11662 Add missing logic to copy case custom fields in CRM_Case_BAO_Case::mergeCases.

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* CRM-11662:
  http://issues.civicrm.org/jira/browse/CRM-11662
Merge pull request #1204 from davecivicrm/CRM-11662

CRM-11662 Add missing logic to copy case custom fields in CRM_Case_BAO_C...