UC-126 update uses of WikiaConfirmEmail messages to use proper methods

Uses of messages from WikiaConfirmEmail.i18n.php were almost all using the escape() method unnecessarily. This was causing a problem for 'wikiaconfirmemail-error-user-not-match' specifically since we want the <a> tag. I fixed that method, but also updated all other uses of messages from this file to plain() since that's more appropriate.