Enhance testing processes - stabilize tests

This is the discussed master issue.

Aleks, Axel and Pavel should create sub-tasks of this with the stuff we discussed:

• Axel: Stabilize autoqa tests
• Aleks: Make sure, all tests always run also in a batch - fix the "Not authenticated" problem
• Pavel: Set up test environment for every developer in our cloud
• Pavel: Set up script that allows with a single command to start the tests for a certain branch, that will be checked out
• Pavel: Set up pipelining with Bitbucket for the tests on pull requests

All developers should read through all created sub-issues and see, if something should be added/changed. And comment accordingly

Pavel should only start, after everyone gave at least a thumbs up, because these are the most complex tasks.