Revert "Drop $article->userCan('edit') check"

This was not the issue, in the end. I jumped the gun.

This reverts commit e3851bbd5969f11a853a081e75aa03b3da99db1c

Change-Id: Iaebd6df0d5a4cd2da7f5523e2d3750ab33e6f542
Merge "Revert "Drop $article->userCan('edit') check""