code: function(time, callback) {
  		callback = callback || function() {};
  		this.promises.push(function delay(done, utils) {
  			setTimeout(function() {
  				done(null, callback(utils));
  			}, time);
  		});
  		return this;
  	}
docs: Sets a promise to delay the execution of the promises.
  
  @param  {!number} time Time in milliseconds to delay the
  execution.
  @param  {!function()=} callback Function to call after the
  delay.
  @return {!ScraperPromise} This object, so that new promises can
  be made.
  @public