Add jobs for extra and dib repos

* add jobs for savanna-extra and savanna-image-elements
* setup pep8 and requirements jobs for check and gate
* setup tarball for pre-release/release and branch-tarball for post
* setup pypi upload for image-elements release

Change-Id: I33b4cf93de3bf98e15e4ff04f231a247b19c3eb5
Merge "Add jobs for extra and dib repos"