Ten years ago, a modest store opened on Boylston Street that would become a symbol of the local-food movement in Jamaica Plain. City Feed and Supply is the kind of meeting place that owners David Warner and Kristine Cortese envisioned. But don't look for farmer's supplies; this is a mecca for people who want to buy what regional farmers produce. Call it a store with a conscience, but the owners call it a place where good old-fashioned local products and local people meet.