Set up CI and static code analysis

[mkrzyzanowski]

• Set up TravisCI integration
  • compile the code
  • run unit tests
• Set up static code analysis
  • pick one of the available options on the market (SonarCloud, Codecov, etc.)
    • Kotlin-specific: https://github.com/arturbosch/detekt
  • add the static code analysis to the build
  • verify that correct quality gates are applied