Aligned setting helper with new get method changes

Also removed old unsused facade that existed for settings.

app/Config/app.php

@@ -183,7 +183,6 @@ return [
 
         // Custom BookStack
         'Activity' => BookStack\Facades\Activity::class,
-        'Setting'  => BookStack\Facades\Setting::class,
         'Views'    => BookStack\Facades\Views::class,
         'Images'   => BookStack\Facades\Images::class,
         'Permissions' => BookStack\Facades\Permissions::class,