Move the random set of HTML files we build from html/ into
the website/ directory.
Also in the website/ directory, put the index.html file from
http://libguestfs.org, which was previously not under version control.
It is generated from index.html.in so we can automatically add the
current version and release date.
Also in the website/ directory, put various CSS file, images, etc.
which are required by the website and were also previously not under
version control.
Change the 'make website' rule to 'make maintainer-upload-website'.
As the name suggests, it is only useful for the maintainer, and will
fail with an error for anyone else.