Remove service worker from cordova-browser

It doesn't make sense to include service workers by default in cordova-browser. We are better off documenting how to add service workers so our users can do that. I think we need to delete https://github.com/apache/cordova-browser/blob/master/bin/template/www/cordova-sw.js and remove any references to cordova-sw.js https://github.com/apache/cordova-browser/search?utf8=%E2%9C%93&q=cordova-sw.js&type=