function classUpdate($el, className, enabled) {
        if (enabled) {
            $el.addClass(className);
        } else {
            $el.removeClass(className);
        }
    }
Add or remove a class, depending on if it's "enabled"

@param {jQuery} $el Element that has the class added/removed
@param {String} className Class or classes to add/remove
@param {Boolean} enabled True to add the class, false to remove