Add noscript tags for fallback content

[DanielPintilei]

The fallback message should be seen only when JavaScript fails to load. Currently, if the app loads on a slow network, it is displayed. I added the tags outside the root element, as seen in the create-react-app template.

[maxmilton]

If we're going to do something like that, I'd prefer we have a better default message:

<noscript>
  For full functionality of this site it is necessary to enable JavaScript.
  Here are the <a href="http://www.enable-javascript.com/" target="_blank" rel="noopener">instructions how to enable JavaScript in your web browser</a>.
</noscript>

Of course it's up to the developer to set things up, but hey, may as well provide sane defaults.