Preprocessor

Pull request #30: Develop to master - repository adjusted against SQAaaS recommendations

Merge in EOSC-RS/preprocessor from develop to master

* commit 'dac9b4f27093ba8668b59a15bea87a073f83575b':
  RS-423 hadolint configuration disabled
  RS-421 CHANGELOG.md updated
  RS-421 DEVELOPERS_GUIDE.md extended with new section 'Software Quality Assurance'
  RS-423 hadolit.sh updated to use 2.8.0-alpine version of hadolint
  RS-423 hadolit.sh + .hadolint.yaml + Dockerfile adjusted to pass the linting
  RS-423 .jsonlintrc with configuration for jsonlint-cli validations
  RS-425 script.py - a dummy file to make the python-based validations not generate false-negatives
  RS-423 checkstyle-suppressions.xml + pom.xml extended with Chechstyle configuration
  RS-424 CITATION.cff
  RS-422 CODE_OF_CONDUCT.md added to CHANGELOG.md
  RS-422 CODE_OF_CONDUCT.md