Create a shareable trim of the website

Some of the code of the website is private.  Create a cut-down version
whose source can be shared with third parties.

Add README file discribing the source code repository.

Change links to Dropbox to a private copy of the files.
Move main stylesheet to a more logical location
Add link to the running version of this website

This, trimmed-down version of the website runs now on Heroku.  Keep the
link to the full version.