bump version of brotli-decompressor to return Result<Write,Write> for…

tests for into_inner on both readers and writers

finish brotli output when into_inner is called

bump version of c extension crate

Fix #39 . added into_inner

Cargo.toml: pointing to the extracted doc

Pointing twice to `README.md` doesn't seem necessary :)

fix some nitpicks in the type system

fix 1.12 build

fix #37

Added header parser facility and tests to make sure it works properly