Formatting

[guygastineau]

I wonder if you want cargo fmt used on the codebase? There are substantial modifications to some files when used. If you want it I will make a PR just for formatting, and I will then cargo fmt any work that I push elsewhere. If you don't want to enforce formatting then I will just try to use sensible conventions that fit with your style in my work without running the tool.

[asomers]

I don't like the way rustfmt handles futures (see https://github.com/rust-lang/rustfmt/issues/2080) so it's my habit not to use it at all. But this crate doesn't involve futures. I'll go ahead and set it up.

[guygastineau]

Okay. I used to have some issues with it, but after not using rust for a while the idea of a formatter is comforting ;)