Refresh implementation (#4)

[bradflood]

Theme: Refresh the implementation based on SQ 6 API; add unit tests; verify Kotlin reporting

• add new unit tests; log rather than throw ex
• add license headers
• apply SonarQube formatting (https://github.com/SonarSource/sonar-developer-toolset)
• verify Kotlin-based mutants are reported correctly
• create new package for Scanner; clarify Metrics
• first adjustments based on execution in SonarQube engine
• polishing