UC-156 Update antispoof to work against the user DB

* Also fix up the UserSignupAjaxForm.js
UC-156 Make sure we don't try to create a SpoofUser object if its not loaded

Also make the code more clear and readable
UC-156 Improve style compliance
Merge pull request #5617 from Wikia/UC-156

UC-156 Update antispoof to work against the user DB