Use Noir sessions in tests

In 5e6af1b, Noir sessions replaced Sandbar sessions. This makes the
same change for tests.
Fix test-do-update-settings

do-update-settings! now takes a theme argument (from 57e8c6d4), so use
that in tests as well by pulling default-theme from utils.
User tests need CongoMongo
Merge pull request #234 from smcgivern/fix-tests

Fix tests