Remove deprecated pool options from defaults

[abenhamdine]

Since the upgrade of pg-pool to version 2.X, some properties seemingly have been removed from the pool options :

• reapIntervalMillis, returnToHead and poolLog no more exist : I didn't find any occurrence of them in the code
• poolIdleTimeout has been replaced by idleTimeoutMillis

I also have changed poolSize to max : while poolSize is still allowed in node-pg-pool, only the option max is documented in the readme, see https://github.com/brianc/node-pg-pool/blob/master/README.md

In configuration test, I added more default properties assertions.

I also changed the pool url to link to node-pg-pool in the comments.

[brianc]

Awesome, thanks! I'll roll here in a bit. Gonna push a new minor version to support statement timeouts too.

[abenhamdine]

Thx for merging !