Update to pg 3.x, support 'or' operator and arbitrary where clauses, all tests run

_Update to pg 3.x._ - Not only has it been out for a long time, version 3 has started to support domains properly. Domains are important.

_support 'or' operator and arbitrary where clauses_ - See readme updates. This syntax is the same as what the [mysql adapter](https://github.com/jugglingdb/mysql-adapter)  supports.

_all tests run_ - The tests in postgres.test.js weren't running. So I fixed that.