update uses of .save(false) to rails 3 style

Change-Id: I9627b75a5473044f9902a5e171a79d4446772ed7
Reviewed-on: https://gerrit.instructure.com/29572
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>
QA-Review: James Williams  <jamesw@instructure.com>