Add the `scripts/setup-hooks.sh` script which sets the following hooks
up:
- The `post-commit` hook runs the linter after every `git commit`,
letting you know if there are code style or rule linter offenses you
need to fix.
- The `pre-push` hook runs the linter and the tests and block the `git
push` if they do not succeed.
This way you realise if everything is alright without the need of
sending a PR.
