Reenable producer/consumer.
DRILL-1249: ensure ResultBatchLoader to check group count to determine if incoming batch has empty values for repeated fields
DRILL-1245: throw more descriptive error messages if i) json file is invalid ii) also display max record size allowed
DRILL-1137: C++ Client. Support setting default schema in the connection phase.
DRILL-1222: C++ Client. Fix DRILL-1144 compilation on Mac OS
DRILL-1226: C++ Client Decimal ignores leading zeros for decimal 9 and 18