Cleanup packaging
- Correct the typo in the package name.
- Move Perl modules to a less surprising namespace.
- Install the files in the correct location instead of /opt.
- Purging the package now actually removes all the data, the user and its group.
- Use systemd to manage both the service and socket file. Consequently the application is run with the expected user and the socket file still has the expected permisions.
- Add tests for the PasswordToken module.
Also make perlcritic happy.