Blender Git Loki

Build bot release pipeline

* downloads builds from builder.blender.org
* generates checksums (still need to cleanup filenames)
* create source archive
* upload to download.blender.org

Next steps
* Next step is to place them in the correct folder
* file permissions download.blender.org
* snap package
* steam packages
* release notes

TODO:
* add more generic functions in master.cfg
* use a separate folder per build

BuildbotLTS: Project Documentation

Added README.md containing a overview of the project.