Add Alembic for DB change management

[lchen-2101]

Context

DB change management tool needed to allow for more automated db schema changes.

Pre-requisites

Task

Implement liquibase or something similar to allow for automated db schema changes from code.

Acceptance criteria

• Add db change management tool

[hkeeler]

Alembic is the standard database migration tool for SQLAlchemy. I think we should stick with that unless there is a very compelling reason not to. Though, I do like Liquibase myself. 😄