DRILL-227: implement simple metrics framework
DRILL-235: Add configuration parameters to control number of threads and width of queries
DRILL-236 ensure that each minor fragment has at least one entry assigned to it
DRILL-237: Add local mode to QuerySubmitter
DRILL-243: lowercase asc/desc in generated physical plans causes failures
DRILL-244: NPE when updating assignment affinity metric
DRILL-245: NPE in ProtoMap (hazel cache)
DRILL-246: Improve command line parsing for QuerySubmitter
revert intellij collapsed imports
Add SingleMergeExchange, which constructs one receiver and many senders (similar to UnionExchange)
Implement stub for MergingRecordBatch
Add test for MergingReceiver (leveraging SingleMergeExchange)
s/MergingReceiver/MergingReceiverPOP/
cleanup.  tests pass with MergingRecordBatch stub.