check if user has full passwordless sudo privileges

[baldwinsung]

fixes #28

[alauppe]

Thanks for this improvement. The core behavior change makes sense: if the user already has passwordless sudo, run-playbook.sh should not force an unnecessary become-password prompt.

I pushed a small follow-up commit onto your branch before merging to keep the behavior the same while cleaning up the wrapper a bit:

• normalize the shell indentation in the new branch
• add a short message so users can see whether passwordless sudo was detected or whether they are being prompted

Appreciate the contribution.