[WIP] Removed usage of /etc/setup/setup.ini

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Related tickets | #5
| License       | GNU GPL v3

- [ ] Added a note that for the version 2.0 `cyg-apt` will not use anymore `/etc/setup/setup.ini`