doc: switch pandoc to html5
doc/rust.HTML: proper version box
doc: tidy and cleanup CSS deps, add tutorial PDF generation
doc: expand tutorial/manual CSS

Cleanup, edit, add some Bootstrap v3.0.0 elements.
rustdoc: nitpicks & cleanup
auto merge of #9868 : adridu59/rust/patch-doc, r=brson

- switch pandoc to HTML5, add tutorial PDF gen.
- cleanup and refactor CSS, expand tutorial/manual CSS +some Bootstrap elements, cleanup unused doc/lib.css

you can see it here in action: http://adrientetar.legtux.org/cached/rust-doc/rust.html
- minor rustdoc cleanups

@alexcrichton