Investigate cockroach DB integration

[bryanchriswhite]

Background

As the graphql API service scales to meat demand, the DB will quickly become a performance bottleneck.

(see: CockroachDB quick start)
(see: CockroachDB comparison)

Acceptance Criteria

We've determined whether CockroachDB can be easily integrated by swapping out the postgres for it:
a. If not, then we've enumerated those pain points / issues
b. If so, then we have a working proof-of-concept

[manjeet-fetchai]

Findings:

• We are able to integrate cockroachdb with N replicas and replace it with our existing postgres
• The genesis import does fine correctly with cockroackdb
• On node startup, we found a few "type errors" - need to debug that [will be a different task]