When $wgReadOnly = true; in LocalSettings.php the edit icons
appear locked and when clicked should show a warning.
This also addresses deprecation warnings in the code and
tidies up the ES6 code.
Note to reviewer: Please use git diff HEAD^ -w
when reviewing this diff. Mostly whitespace changes.
Change-Id: I3fa83cc1dc4da62260fd0ef50ac14805c3e1282b
