Minor fixes for Timberland dracut

[mwilck]

Two minor fixes for the dracut code

Note about branches

This PR goes into the timberland_master branch, which I have used for the upstream PR https://github.com/dracutdevs/dracut/pull/2184, too. That branch is going to be rebased onto upstream dracut until the upstream PR is merged.

Changes

• suppress pointless hostname warning
• support config.json

Checklist

• [x] I have tested it locally
• [x] I have reviewed and updated any documentation if relevant
• [ ] I am providing new code and test(s) for it

Fixes #4.

[mwilck]

Superseded by #7.