* Add connection & query timeout if all clients are checked out
This addresses [pg#1390](https://github.com/brianc/node-postgres/issues/1390).
Ensure connection timeout applies both for new connections and on an exhuasted pool. I also made the library return an error when passing a function as the first param to `pool.query` - previosuly this threw a sync type error.
* Add pg-cursor to dev deps
