ROCKLAND, Maine — For the last two months, patrons of Rock City Coffee might not have noticed any changes when they stopped at the busy downtown cafe for their regular order. That’s exactly what the new owners — the people behind the counter — want. Two months ago, Rock City Coffee, a cafe and coffee roastery, became a worker-owned cooperative, with employees buying the business from its previous owner and founder, Susanne Ward. For Ward, selling the business to her employees was a reward to people who worked for her and a way to ensure that what she and her husband began 26 years ago would live on true to character. For the employees, the opportunity allowed them a path to business ownership and to keep Rock City as the place where they love to work.