module.exports = {
  //database user's name
  user: process.env.USER,

  //name of database to connect
  database: process.env.USER,

  //database user's password
  password: null,

  //database port
  port: 5432,

  //number of rows to return at a time from a prepared statement's
  //portal. 0 will return all rows at once
  rows: 0,

  // binary result mode
  binary: false,

  //Connection pool options - see https://github.com/coopernurse/node-pool
  //number of connections to use in connection pool
  //0 will disable connection pooling
  poolSize: 10,

  //max milliseconds a client can go unused before it is removed
  //from the pool and destroyed
  poolIdleTimeout: 30000,

  //frequeny to check for idle clients within the client pool
  reapIntervalMillis: 1000,

  //pool log function / boolean
  poolLog: false,

  client_encoding: ""
};

module.exports = {
  // database host defaults to localhost
  host: 'localhost',

  //database user's name
  user: process.env.USER,

  //name of database to connect
  database: process.env.USER,

  //database user's password
  password: null,

  //database port
  port: 5432,

  //number of rows to return at a time from a prepared statement's
  //portal. 0 will return all rows at once
  rows: 0,

  // binary result mode
  binary: false,

  //Connection pool options - see https://github.com/coopernurse/node-pool
  //number of connections to use in connection pool
  //0 will disable connection pooling
  poolSize: 10,

  //max milliseconds a client can go unused before it is removed
  //from the pool and destroyed
  poolIdleTimeout: 30000,

  //frequeny to check for idle clients within the client pool
  reapIntervalMillis: 1000,

  //pool log function / boolean
  poolLog: false,

  client_encoding: ""
};

Add default value for connection host.
Add default value for connection host.

Native binding connection tests will fail if the PGHOST environment variable is not set.

There already exists several defaul values for user, password and port. It would make sense to have a default host setting as well - localhost appears to be a reasonable default.
