spec: fix "undefined method 'url_for'" in plugin specs
spec: fix "undefined method 'url_for'" in plugin specs

Change-Id: I9d48193fd11ee6ede0cb1e49a8875923ca8d3ebf
Reviewed-on: https://gerrit.instructure.com/75001
Tested-by: Jenkins
Reviewed-by: Joel Hough <4816dabf8db1bc6cac35b3a24cab2ff844b5b0c7@instructure.com>
Product-Review: Alex Boyd <6bb5a335b0b6c251e818c0de653d342158f949f9@instructure.com>
QA-Review: Alex Boyd <6bb5a335b0b6c251e818c0de653d342158f949f9@instructure.com>

sfu/canvas-lms,matematikk-mooc/canvas-lms,roxolan/canvas-lms,SwinburneOnline/canvas-lms,venturehive/canvas-lms,instructure/canvas-lms,HotChalk/canvas-lms,SwinburneOnline/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,dgynn/canvas-lms,SwinburneOnline/canvas-lms,djbender/canvas-lms,grahamb/canvas-lms,matematikk-mooc/canvas-lms,fronteerio/canvas-lms,roxolan/canvas-lms,dgynn/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,roxolan/canvas-lms,grahamb/canvas-lms,fronteerio/canvas-lms,djbender/canvas-lms,matematikk-mooc/canvas-lms,roxolan/canvas-lms,fronteerio/canvas-lms,dgynn/canvas-lms,HotChalk/canvas-lms,HotChalk/canvas-lms,sfu/canvas-lms,SwinburneOnline/canvas-lms,fronteerio/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,grahamb/canvas-lms,instructure/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,grahamb/canvas-lms,venturehive/canvas-lms,instructure/canvas-lms,dgynn/canvas-lms,HotChalk/canvas-lms,grahamb/canvas-lms,venturehive/canvas-lms,instructure/canvas-lms,matematikk-mooc/canvas-lms