Eliminate off-server export code:
- Completely eliminate export service from client interface.
- No longer advertise data sources in messages to off-server clients
- Nobody actually cares about the returned result from EE.exportAction,
  so make it go away.
- Remove dead code.
- Get rid of the message part of ExportProtoMessage.  Make the
  AdvertisedDataSource which everyone uses a first-class object.
- We don't need bootClient() any more since it was for off-server export
  only.
ENG-5316 Handle Dummy catalog.
ENG-5316 javadoc update.
ENG-5338 fix. add log to dump export configuration.
ENG-5316 dont do export checking if dummy catalog.
Merge branch 'master' into ENG-5316
Merge branch 'master' into ENG-5316
Merge branch 'ENG-5316' of https://github.com/VoltDB/voltdb into ENG-5316
ENG-5316 review changes.
Log previously ignored error condition at INFO to reduce panic.
Merge branch 'master' into ENG-5316
ENG-5316 make dummy isPlaceHolderCatalog
Merge pull request #911 from VoltDB/kill-offserver-export

Eliminate off-server export code
Merge pull request #916 from VoltDB/ENG-5316

Eng 5316
Merge branch 'master' into ENG-5374