Stakkr

Fix a bug in stakkr-init

- Upgraded all dependencies
- Traefik 2.x with dashboard
- All files are in docker compose version 3.8
- Https by default
- No more print but use only stdout and stderr
- py.test capture instead of reading stdout from Popen
- Drop Support of python 3.5

Fixed dependencies to avoid crash when one changes

Fixed bug when no workdir is specified

Force workdir to be current dir if not set

Added workdir in exec command