"I vote, because I should have a voice in government," Philip Greenberg was saying one sunny morning recently as he sat in the parlor of Seven Acres Jewish Senior Care Services, his residence since 2005. "That's a problem when no one takes advantage of it."....Greenberg, 101, cast his first presidential vote for FDR and was a Democrat for decades, but not anymore. "I'm a staunch Republican," he said. "I don't mind telling anyone."[Centenarians] represent the fastest-growing segment of the population in terms of age...........Seven Acres, home to nearly 400 residents, requests 100 mail ballots every election year.......Anna Robinson has not...