CRM-13632 relationship update functions, call pre, post hooks on enable, disable, update correctly from api when id is set

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* CRM-13632: Post Hook not called when a relationship is disabled via cron
  http://issues.civicrm.org/jira/browse/CRM-13632
Merge pull request #1836 from eileenmcnaughton/CRM-13632

CRM-13632 relationship update functions, call pre, post hooks on enable,...