PoC PostgreSQL reader

[clevinson]

Basic proof-of-concept for indexing blockchain state (ecocredit & data modules primarily) into a relational database.

Best candidate is probably postgresql, though could involve using other db's if we wanted (e.g. cockroachdb)

[aaronc]

Ref #101. Let's stick with Postgres/postgis for now please. It's what the registry is using no need to spend innovation tokens here.