kano-updater: A bit of refactoring

Mainly moved parts from the kano-updater script to utils.
Adding .gitignore
Adding the --debug argument

This disables re-launching the updater for testing purposes.
Revamping pre and post install scripts

The pre and post update process was too simple to work for us. This
commit replaces it with a more automated version. We need to specify
the individual steps between versions and the updater will figure out
which of those need to be called.

Related to https://github.com/KanoComputing/peldins/issues/735
Merge pull request #9 from KanoComputing/update-scenarios

Update scenarios