application logging

- added logs folder path to `.gitignore`.
- removed redis-server password from `example_conf.yml`.
- added logging statements to `baseresource` and `rosafactory` classes.
- added `banner.txt` to `main/resources`.
Example config seems useful to keep in the repository as a form of
documentation. Maybe let's revert the commenting out of that one line for
now and figure out the wider question later?