Changed to use scala 2.12.4 as default scala version.
Changed to use scala 2.12.4 as default scala version.

scalatest/scalatest,scalatest/scalatest,dotty-staging/scalatest,dotty-staging/scalatest,scalatest/scalatest,cheeseng/scalatest,cheeseng/scalatest,cheeseng/scalatest,dotty-staging/scalatest