Return a dummy client response to SPI for mispartitioned transactions.
Refactored TableStreamer so that clearing the elastic index will never fail.

There's no API to check if the index exists or not. It's hard for the caller to
clear the index without keeping track of the state. Making index clear never
fail so it's always safe to clear even if the index does not exist.
Removed unused method from ElasticHashinator.
Remove m_isIv2Enabled variable from ClientInterface.
ENG-4899: Return the current hashinator config with the version number.
ENG-4899: Include the hashinator config in mispartitioned txn response.

The ClientInterface will use this to update its hashinator lazily.
ENG-4899: Add convenient SyncCallback to SimpleClientResponseAdapter.

Can be used to block on the client response.
ENG-4899: Mispartitioned txn restart work in ClientInterface.

- Update the hashinator with the config in response. That's supposed to contain
  a more up to date hashinator.

- Don't restart the txn during command log replay.
ENG-4899: Add @GetHashinatorConfig sysproc to SystemProcedureCatalog.
ENG-4899: Add addToken() to ElasticHashinator to create a new hashinator with
one more token on the ring.
Merge branch 'elastic' into ENG-4899

Resolved conflicts:
	src/frontend/org/voltdb/ElasticHashinator.java
Merge pull request #749 from VoltDB/ENG-4899

ENG-4899: mispartitioned txn restart handling on command log replay