update terms-of-use and privacy-policy urls

test plan:
 - terms of use link should go to
   http://www.canvaslms.com/policies/terms-of-use
 - privacy policy link should go to
   http://www.canvaslms.com/policies/privacy-policy

refs CNVS-13942

Change-Id: I7b17e278d295ddc1b2a1508352b76aa7f2d30ace
Reviewed-on: https://gerrit.instructure.com/37450
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Jon Willesen <jonw@instructure.com>
QA-Review: Clare Strong <clare@instructure.com>
Product-Review: Jon Willesen <jonw@instructure.com>