Don't double count bytes and rows in RecordProjectOperator
Fix release notes for 0.67
Fix warnings in HiveBucketing
Fix handling of Hive tables bucketed on string
Add 0.68 release notes
Fix Hive bucketing test
[maven-release-plugin] prepare release 0.68
[maven-release-plugin] prepare for next development iteration
Increase parallelism in unit tests to 4