move the contributing hook into hack, and use curl in the same way as the gofmt above

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au> (github: SvenDowideit)

Docker-DCO-1.0-Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au> (github: SvenDowideit)