* introduce a domain specific object model
* service layer wip
* core and contribs wip
* remove repeated external storage access in state machine
* cassandra module changes
* redis persistence changes
* mysql persistence changes
* postgres persistence changes
* redis concurrency limit module changes
* updated IndexDAO APIs and corresponding ES implementations
* more changes per indexDAO api
* fix tests in es modules due to new contract
* fix unit tests as per new models
* rename objects and classes
* fix integ tests