MWS: Anonymous access to wikis when disabled

[Jermolene]

Steps to reproduce:

1. Start with a fresh install of MWS
2. Run npm install and npm start
3. Visit http://127.0.0.1:8080/ in a browser
4. Click the button "Add Admin Account"
5. Enter suitable details for an admin account and click "Add User"
6. Verify that the "Anonymous Access Configuration" dialogue shows that anonymous reads and writes are both disable (see below)
7. In a different browser, open http://127.0.0.1:8080/
8. Click on a link to one of the wikis and observe that access is granted incorrectly

cc @webplusai

[Jermolene]

Update:

I noticed that if I click "Save changes" on the "Anonymous Access Configuration" and then attempt access in the secondary browser again then I do receive the expected 401 error – although also incorrectly receiving a 404 for the favicon:

[Jermolene]

Tests were performed with the commit ddfc8c4