Default Logger to os.Stdout

[c0d1ngm0nk3y]

fixes #46

Summary

Uses Stdout as default log target.

Use Cases

By default, the bard.Logger is an empty object and does not log anything. Adding the logger to the factory function, is not really an option since it would be incompatible and need a major version bump. This change makes sure that the logs are at least written to stdout by default and since Logger is public, it can then be modified.

Checklist

• [X] I have viewed, signed, and submitted the Contributor License Agreement.
• [X] I have linked issue(s) that this PR should close using keywords or the Github UI (See docs)
• [X] I have added an integration test, if necessary.
• [X] I have reviewed the styleguide for guidance on my code quality.
• [X] I'm happy with the commit history on this PR (I have rebased/squashed as needed).

[c0d1ngm0nk3y]

Apparently it is somehow expected to hide log messages by default (see comment)