* 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