ISPN-2803 Ensure the updatedKeys set doesn't get reinitialized erroneously when state transfer completes.
ISPN-2804 Added executor to clean up the completed transaction table.
Slight cleanup

* Javadoc for getNormalizedHash() in Util and ConsistentHash
* Remove redundant "normalization" checks in ConsistentHashV1.getServer()
Updated versions to 5.2.1-SNAPSHOT