no user visible behavior change
test plan:
* make sure existing wiki contents haven't disappeared
* make sure a new course gets a wiki that functions correctly
* make sure wiki rss feeds are still functional
* try to access the wiki from a new course from multiple requests
simultaneously; it should get a single wiki that's not conflated
Change-Id: I339b56c39d7868dbdec3df4007291a429272b1cf
Reviewed-on: https://gerrit.instructure.com/12432
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Brian Palmer <brianp@instructure.com>
Cody Cutrer