Update index.html

add footer.
Update main.css

add css for footer
Update index.html

change footer with css
Merge branch 'patch-3' of https://github.com/sfahrenholz/duplicati
Merge branch 'patch-4' of https://github.com/sfahrenholz/duplicati
Merge branch 'patch-5' of https://github.com/sfahrenholz/duplicati