Rustfmt

I went to fix the clippywarning but 2/3 of them were redundant_field_names which rustfmt can fix automagicly.

I also switched the rustfmt container image to a prebuilt one and enabled it on the CI.

https://rust-lang-nursery.github.io/rust-clippy/v0.0.187/index.html#redundant_field_names