By Gram Slattery HOLLIS, New Hampshire (Reuters) – Nikki Haley and her allies are flooding New Hampshire with campaign workers and sharpening their attacks on frontrunner Donald Trump as they angle for an upset in next week’s Republican presidential primary. AFP Action, a political advocacy group backed by conservative billionaire Charles Koch, is sending up to 100 additional employees to knock on doors in the final sprint ahead of Tuesday’s vote. SFA, another deep-pocketed PAC supporting Haley, released a new ad this week featuring New Hampshire residents calling Trump a bully and a liar. And…