GitLab

this component initializes an DockerClient on startup,
then provides a method to run an container with an given image String
and n given Bind-mounts.
This method waits for this container to finish before returning,
so don't call any services that should just be started and left alone!

For this the library github-java-docker is used:
https://github.com/docker-java/docker-java

For this to work, the container this is run in obviously needs
access to the docker socket

- defined modocot URI for unittests and submissions
- directly expect a textfile, not an archive
- store config file and local repo copy in persistent place,
    instead of using Gitea

BREAKING CHANGE: file to be uploaded changed from zip to text
BREAKING CHANGE: no longer uses Gitea

- removed proxy setup method
- reworked clone method

BREAKING CHANGE: method signature for cloneRepository changed