MLOps with Azure ML

Upgrade build train CI pipeline to multi-stage (#90)

* add staged pipeline

* remove release id

* remove train in release pipeline

* revert to BASE_NAME vars

* Move train trigger to new stage

* cleanup register comments

* add conditional for triggering train pipe

* update doc steps

* string vs boolean

* var to boolean

* set to false

* try with true

* cleanup images

* Use Coalesce so override works

* add back build artifacts

* address feedback

* include code/scoring path for ci