CRM-12634 Simplified fix using crmURL.

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* CRM-12634: Return to home page link on upgrade finish page doesn't need to rebuild menus
  http://issues.civicrm.org/jira/browse/CRM-12634
Merge pull request #1097 from davecivicrm/CRM-12634-2

CRM-12634 Simplified fix using crmURL.