fix installation of ProtoBuf for TensorFlow
fix installation of ProtoBuf for TensorFlow

ChicagoBoothAnalytics/DataWrangling_inR,ChicagoBoothAnalytics/DataWrangling_inR,ChicagoBoothAnalytics/HelpRFun,ChicagoBoothAnalytics/HelpRFun,ChicagoBoothAnalytics/HelpRFun,ChicagoBoothAnalytics/DataWrangling_inR