Introduce commit signoff and changelog check into integration.
Introduce commit signoff and changelog check into integration.

Changelog: None
Signed-off-by: Kristian Amlie <505e66ae45028a0596c853559221f0b72c1cee21@mender.io>

GregorioDiStefano/integration,pasinskim/integration,pasinskim/integration,pasinskim/integration,GregorioDiStefano/integration