upgrade to rspec 3

fix a blocking thing, and add a compatibility gem

and a few final missed things

fixes CNVS-16239

Change-Id: I6ffa4569f936173393eaf7225f7463a4ccba1c7c
Reviewed-on: https://gerrit.instructure.com/42715
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Braden Anderson <braden@instructure.com>
Product-Review: Braden Anderson <braden@instructure.com>
QA-Review: Braden Anderson <braden@instructure.com>