screenshots: minor compression improvements with kraken.io.
Update files for 1.7.7.
changelog.md: Fix version and date.
Add a new `date` variable in _config.yml.

This way it should be less error-prone
Use Font Awesome in more places.
changelog.md: minor tweaks.
Add the old SF news.
Merge pull request #40 from mpc-hc/old-news

Add the old SF news.
Add navigation support in news posts and archive.

The whole patch is a sort of hack since Jekyll's Paginate doesn't work unless it's in a page named "index.html".
Merge pull request #41 from mpc-hc/paginate

Add navigation support in news posts and archive page.
Tweak mobile view.
Add a dropdown navbar menu and icons.
More tweaks for thumbs.