Schema inference not supported on CockroachDB

[jethrogb]

Thanks to CockroachDB's protocol compatibility, it almost works out of the box. There are just some minor things that need fixing:

• In Postgres terms, CockroachDB does not have databases. Only schemas inside a single database. This breaks inference (unless your database is named “public”).
• CockroachDB's information_schema.columns.data_type values are different.
  • INT is diesel::types::BigInt
  • STRING is diesel::types::Text
  • (others?)

You can detect CockroachDB like so: SELECT version() LIKE 'CockroachDB%';

Of course, to make the example code work with BigInt, I also needed to change the Rust datatype in the model and code to i64.

[theduke]

Duplicate of #1134, so one of them can be closed.
This issue is older, but the other one has more disussion.