DES MOINES — Iowa Democrats dispelled talk of an enthusiasm gap Friday, cheering on their 2016 candidates and pledging to press full speed to the Nov. 8 finish line in hopes of winning the state for Hillary Clinton and scoring gains up and down the general-election ballot.“It’s the countdown to the election of our lifetime,” Iowa Democratic Party chairwoman Andy McGuire told about 560 Democrats who gathered for the party’s fall fundraising gala, which featured pep-rally style speeches from party rising star Texas Congressman Joaquin Castro, former Gov.