GitLab

- Change navigation of docs to be more structured
- Add diagram on flow engine container layering
- Fix markdown to be compliant to linting rules
- Add links to imprint and privacy policy and fix typos
- Add link to sourcecode repository and add small logo
- Fix docker tag usage with images for build steps

* Use image that includes libczmq also for running

HOTFIX-log-message: fixed the logger package in repo.go to dbConnector and refactored the ReadMessage

The bricks now have constraints that allow the devs to add RegExp to validate the parameter before it can be saved

* and fix paramter conversion in  gridmanager

 - added the title for architecture image in docs/index
  - removed the text duplication for service links from docs/index

 -  removed the duplication from packagemanager docs
 -  removed the duplicated docs "communcation in titange" and "how to configure loggin" since there are exist in flowengine-py doc.

* cleanup parameter conversion in flowmanager/gridmanager to support secret-typed
parameters

Packagemanager requires UJASchema to be present and thus must be based
on a Python 3.7 on Alpine image