Integrate gitlab-ci/make-distro-and-image-combos-dynamic and 2 more

--

Commit: seco-ne/yocto/infrastructure/gitlab-ci@a08a6a97

Make distro and image combos dynamic

--

Commit: seco-ne/yocto/infrastructure/gitlab-ci@414ebe6d

Add python code analysis via sourcery

Disable all checks which do not pass currently. These should be enabled
in the future along with a code refactoring to make them pass.

--

Commit: seco-ne/yocto/infrastructure/gitlab-ci@df817ecf

README: Add howto to create a new project.