ENG-5259: Remove redundant index snapshot request API from
CommandLogReinitiator.
ENG-5259: Refactor a utility method in IndexSnapshotWritePlan for reuse.
ENG-5259: Replay @BalancePartitions fragment tasks during live rejoin.
Merge branch 'master' into ENG-5259
Extract gzip compression code from ElasticHashinator to CompressionService.
ENG-5259: Fix replay of sysproc fragments during live rejoin.

Lost my changes accidentally during branch switching!!! Here they are again.

Create the correct fragment task based on the type of the fragment task
message. If it's a sysproc fragment, replay it. The site should be guarding what
and what not to replay.
Merge pull request #875 from VoltDB/ENG-5259

ENG-5259: Rebalance and rejoin