Architecture - Phase 1 - Creating room

# Create room for change, without changing behavior

* Introduce a ```WorkflowContext``` object, passed through all chain processors
* Standardize a ```HandlerResult``` envelope
* Add correlation IDs / Actions IDs consistently to logs, db entries etc.
* Add a startup validator for config/registered handlers
* Create a 'shim' between old handler signatures and new - for any externally written handlers

Non-breaking rule

* no config changes.
* Existing chain order remains preseved and source of truth
* This is internal refactoring's only

*Grovesy working on this issue, will @ when ready