Update release notes for release 1.6.0
Add helper methods to create cluster and storedefs
Add non-contiguous shuffle and cluster expansion planner test
Add non-contiguous zones/nodes tests to ZonedRebalanceBatchPlan

Added shuffle and cluster expansion tests to rebalancebatchplan
in presence of cluster with non contiguous zone and node ids.
StoreRouting plan tests with non contiguous zones/nodes
PartitionBalanceTest with non contiguous zone/node ids
ZoneRoutingStrategyTest with non-contiguous zone/node ids
RepartitionerTest with non contiguous zone/node ids
Address code review comments
Added fix related zone id on server side

The server previously enable server side by default. It creates a routed store
inside storage service using default zone id(0). In a cluster with no zone0, the
server will fail to start due to zone 0 not found. This fix turns off the server
side routing by default and also fix the issue by using sever's specific zone id
instead of a static value(0)
Refactored zoneAffinity Test; add non contigious ids test cases
fix storage service test affected by turning off server routing
added test to support non contiguous zone and node ids in test cases
Zone Affinity test fix
AdminServiceBasicTest with non contiguous zone/node ids
AsyncMetadataVersionManager with noncontiguous zone/node ids
StorageService Test with non contiguous zone/node ids
ZoneCountWriteTest with noncontiguous zone/node ids
Address review feedback