Revert "[maven-release-plugin] prepare for next development iteration"

This reverts commit 387892353f1f8abcce25f762bcd438ffb39a4f0d.
Revert "[maven-release-plugin] prepare release v0.8.0-incubating"

This reverts commit 75bd03e4d9a6605e96c6dd405ef09b4975495f61.
Revert "Hard code scala version in pom files."

This reverts commit a1e7e519653beae47cafccbb9e335bc74986c0dc.
Revert "Revert "Hard code scala version in pom files.""

This reverts commit ce6b881db90f6cec76789f6f9d0e66480327dde4.
[maven-release-plugin] prepare release v0.8.0-incubating
[maven-release-plugin] prepare for next development iteration