Merge pull request #500 from jay-hodgson/develop

SWC-658: merge down from release-y
Add cloudwatch metric for dynamo worker latencies
Add metric to dynamo rds synchronizer
Move node-tree update manager to the managers package
dao done
Fix test errors
Move Change to be the last migration type
Add StorageQuota DTO to handle e-tags
Merge pull request #501 from eric-wu/develop

Add metrics to dynamo workers
Improve the performance of isRoot() to constant time
Merge pull request #503 from eric-wu/release-y

Improve the performance of isRoot() to constant time
Merge branch 'release-y' into develop
Merge remote-tracking branch 'upstream/develop' into develop
started manager and workers
Merge branch 'release-y' into develop
Fix a bug of demoting a root.
Replace NullPointerException with IllegalArgumentException
Add exception for multiple parents
Add handling of MultipleParentsException
Increase throughputs