Manual pipeline support for '--jobs'

Closes #23 and fixes tests as pointed out in !45 (merged).

Coverage added.

split IT and UT execution:

• UT - run everywhere, fail if coverage is less than 62% as of Sep 26, 2019
• IT - run only on the main repo - finestructure/pipeline-trigger with all necessary secrets configured. Prior behavior: Failing tests on other contributors forks are misleading and not helpful.

GitLab pages job configured to display coverage reports. @sven.schmidt now you can configure Coverage Badge on your repository.