Fix Protobuf version clone on unix (Fix google#620).

Fix wheel pure lib generation (google#616)

add data file to rcpsp notebook

September 2017 release of OR-Tools.

September 2017 release of OR-Tools

OR-Tools August 2017 release

July 2017 release of or-tools

OR-Tools June 2017 release v6.1

May 2017 release: v6.0

support twine