#1 Force browser to refresh

[Sean Morrison]

This is a really simple little patch that will force the browser
to refresh via http header directives. I was having continual
problems with the browser cacheing pages and I'd forget to
hit refresh. Kept thinking there was something wrong with
simpletracker. Asking the browser to kindly not cache the
pages seems to do the trick.

I only updated the index.php as it seemed to be what
everything goes through. If there are other external .php's,
they might benefit from the same headers if they have
dynamic content.

Cheers!

[Sean Morrison]