api/v3/Setting - Better reporting of errors
CRM-13768 - CRM_Core_BAO_Setting - Fire on_change events

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* CRM-13768: CiviCase not fully activated during extension installation
  http://issues.civicrm.org/jira/browse/CRM-13768
CRM-13768 - api_v3_SettingTest, CRM_Core_BAO_SettingTest - Test for on_change event

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* CRM-13768: CiviCase not fully activated during extension installation
  http://issues.civicrm.org/jira/browse/CRM-13768
CRM-13768 - enable_components - Use same logic when toggling components via API and web UI

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* CRM-13768: CiviCase not fully activated during extension installation
  http://issues.civicrm.org/jira/browse/CRM-13768