Update govuk toolkit and template

* govuk_frontend_toolkit: 0.48.0
* govuk_template_mustache: 0.8.0
Update govuk template and govuk frontend toolkit
Remove elements header include

* Remove elements Sass file, include in application.scss
Update application css and elements styles
Remove unused routes
Remove unused templates, update elements pages
Set up page content styles

* Update elements stylesheet
* Import into application stylesheet
Add govuk icons
removed nodemon for windows
new protoptype test
fixing errors with merge