Better checking of namespace

We're aiming to get this into release-238 for release tomorrow. This PR is to dev, which will then be cherry-picked into the release branch.

https://wikia-inc.atlassian.net/browse/VE-1397
So, my understanding is that click on red link triggers ultimately call to CreatePage.requestDialog or not (if certain criteria are not met). I see now that some conditions are checked in one place (this anonymous function), other in another (inside redLinkClick). I don't think it make easier to understand and follow. Any reasons for that?