DRILL-903: Cleanup exising ValueVectors before allocating new ones in StringOutputRecordWriter.updateSchema.
DRILL-869: ExprParser fails when operators have space in name.
DRILL-892: Send Batch is leaking memory when send fails to establish connection to remote fragment.

Also:
1. Maitain one StatusHandler for all OutgoingRecordBatches in Partitioner.
2. In FragmentExecutor check for failures set in FragementContext.
Enable FragmentExecutor to catch assertion errors and return to client.
Support multiple output batches for hash aggr.
DRILL-574: Fix RPAD to truncate from right, when desired length is smaller than input length.
DRILL-901: Fix Parquet read bug with VarBinary.

Also now throw an exception if parquet reader is not passed any columns found in the file. Previously a NPE was thrown as the setup method exited early, skipping an object initialization that manifested in the first call to the next method.
Turn off invalid project push down tests until DRILL-912 is fixed.