Move the generated date from the top of the page to the footer.

It's useful reference information, but anyone who wants it will look
for and find it.  We don't need this front-and-center.  Follow the
pattern set by our header template with a triple-quoted string.

The gray <hr> styling is less agressive.  IE uses 'color' for drawing
the rule, while Gecko and Opera use the border or 'background-color'
[1].

[1]: https://bugzilla.mozilla.org/show_bug.cgi?id=239386