fix some rspec deprecation warnings

Change-Id: Ibcaf3116888d364e9e291bbc91816ec21f90e1ff
Reviewed-on: https://gerrit.instructure.com/37405
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: James Williams  <jamesw@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>