Set default for MapReduce Action and enabled MapReduceAcceptanceTest
Added tests for proper handling of errors with multiple batches
Removed requestStart, requestDone, and requestEnsureConnection in DB class.

  JAVA-1544
Fixed some InsertOperation tests of unacknowledged writes
Normalised SingleConnectionBinding and AsyncSingleConnectionBinding

Put both in driver-core/src/test
JAVA-1547
Fix race condition in test
Added DBCollection apply/doApply to clirrexclude.yml

 JAVA-1538
Added DB requestStart/requestDone/requestEnsureConnection to clirr-exclude.yml

 JAVA-1544