Honor default separator in set_config

[kajinamit]

... to use the consistent separator by default in all functions by default. Users can still override the separator by passing the separator argument when calling the function.

Fixes: #544

Summary

Provide a detailed description of all the changes present in this pull request.

Additional Context

Add any additional context about the problem here.

• [x] Root cause and the steps to reproduce. (If applicable)
• [x] Thought process behind the implementation.

Related Issues (if any)

#544

Checklist

• [ ] 🟢 Spec tests.
• [ ] 🟢 Acceptance tests.
• [x] Manually verified. (For example puppet apply)