ENG-4237: Accept a null deployment string in
UpdateApplicationCatalog.  Use the previous deployment settings in
this case.
ENG-4237: Allow @UpdateApplicationCatalog to pass through to the
replica without killing it.
ENG-4237: Need to preserve DR properties (invocation type, original
txn ID, unique txn ID) as the catalog work traverses through the async
compiler thread.
ENG-4237: Fix up/enhance a client interface check to verify that the
DR-needed info from the master is getting passed along properly.
Merge pull request #381 from VoltDB/eng4237

Eng4237