Fixed unit test testYamlAbsoluteFileInclude
Fixed unit test testYamlRelativeLocalFileInclude
Fixed unit test testIncludeWithMissingDirectoryRaisesException
pylint cleanup of liquibasedb_test.py
pylint cleanup of sample_test.py
Fixed unit test xmlwriter_test.py
pylint cleanup
Fixed contamintaion of source tree with liquipy_changelog.xml file in sample_test.py