rspec 3-ify gems/plugins

refs CNVS-16239

Change-Id: Ib86dd5f161128a241a6c2d0d21af79e3ec3d53ec
Reviewed-on: https://gerrit.instructure.com/42878
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>