ENG-4336: Pass isRejoin flag to the PartitionDRGateway constructor.
Log transactions to DR during live rejoin replay from task log.
Guard debug log messages with log.isDebugEnabled().
ENG-4336: Use IGNORED_TRANSACTION response for DR duplicate transactions.

So that the ClientInterface can forward this response to the DR agent
directly. Otherwise, ClientInterfaceHandleManager will generate a failure
response.
ENG-4336: Fix parameter ordering of PartitionDRGateway.getInstance().
Merge pull request #384 from VoltDB/ENG-4336

ENG-4336: Various DR fix ups.