Update for upstream changes
Merge pull request #22 from adrientetar/upstream

Update for upstream changes
Changed "Other docs" to "All docs". Changed "docs" link to "all docs"
Add rustup.sh
rustup doesn't need to write config.tmp
Romove POPL instructions
Add install.html
Complete overhaul
Hedge footnote
Trim the fat

- Switch to Jekyll templating
- Cleanup some HTML markup
- Make it responsive
- Fix some metrics
- Add Fira webfont
- TODO: cleanup unused/dupe CSS