Adding pylint configuration, VSCode configuration to lint on save and
make the deploy.py script compliant.

- Check that JLinkExe in properly installed
- Verify that the app is installed
- Always report failures in the exit code
- Add vscode settings for Python code formatting using Google style
- Fix issue #42 regarding tockloader version and sticky parameter

Updated the shell script that generates the certificates and the
documentation accordingly.
Caveat: now installation is a 2-step procedure, installing OS and
application are split into 2 commands.