Current and former employees of the gourmet coffee chain filed a federal complaint yesterday claiming their corporate bosses have refused to heed repeated warnings about inadequate training and chronic infestations of roaches, rats and other vermin in New York stores. But the company strongly denied the allegations, noting the complaints were coordinated by a handful of activists who are trying to unionize the chain's normally merry band of baristas. Out of the 201 Starbucks stores in the city, the Department of Health issued notices of violation to 44 for rodent or insect activity in the most recent round of inspections,...