connect-pg-simple 6.0.0 on Node.js NPM

Breaking change: Now requires at least Node.js 10.x, this as Node.js 8.x only have a short time left in its LTS
Breaking change: This project now uses INSERT ... ON CONFLICT, more popularly known as UPSERT. This is only supported on PostgreSQL version 9.5 and above.
Update pg-promise dev dependency to 9.x
Listen on pool errors. Fixes #29
Lots of dev dependency updates