DRILL-1596: Build schema for producer-consumer
DRILL-1595: Send intermediate fragments before leaf fragments
DRILL-1599: Drill FileSystemPlugin need getOptimizerRules() method to get optimizer rules from format plugin
DRILL-1333: Flatten operator for allowing more complex queryies against repeated data.
DRILL-1600: Enable Java assertion in unit tests
DRILL-1604: Include error info in message sent back to client