Add upgrade / migration functionality to api

**Is your feature request related to a problem? Please describe.**
If and when a breaking change is made as part of an upgrade, we need to upgrade/migrate existing data/schemas.

**Describe the solution you'd like**
Build a generic data migration/upgrade solution on API startup.
1. Check current app schema version.
2. If requires upgrade, create copy of master Dataset, execute all version upgrade scripts in sequence to get to the necessary version.
3. Validate.