code: function PostgreStore(conString, options) {
      if(!conString){
          throw new Error('Connection String is missing.');
      }
  
      this._options = options || {};
      this._options.pgstore = this._options.pgstore || {};
      this._difficulty = this._options.pgstore.difficulty || 10;
  	this._table = this._options.pgstore.table || 'passwordless';
  
      this._client = new pg.Pool({
          connectionString: conString,
          max: this._options.pgstore.pgPoolSize || 10
      });
  
      if(!isNumber(this._difficulty) || this._cost < 1) {
          throw new Error('bcrypt difficulty must be an integer >= 1');
      }
  
      delete this._options.pgstore;
  
      var self = this;
      this._client.connect(function(err, client) {
          if(err) {
              throw new Error('Could not connect to Postgres database, with error : ' + err);
          }
      });
  }
docs: Constructor of PostgreStore
  @param {String} conString URI as defined by the PostgreSQL specification. Please
  check the documentation for details:
  https://github.com/brianc/node-postgres
  @param {Object} [options] Combines both the options for the PostgreClient as well
  as the options for PostgreStore. For the PostgreClient options please refer back to
  the documentation. PostgreStore understands the following options:
  (1) { pgstore: { difficulty: integer }} to change the bcrypt difficulty. Defaults to: 10
  (1) { pgstore: { table: string }} to change the name of the table used. Defaults to: 'passwordless'
  (2) { pgstore: { pgPoolSize: integer }} to change the pool size of PostgreSQL client. Defaults to: 10
  @constructor