West Village's tiny grocer is beginning to grow. Since opening last spring, Parker Street Market has completely filled its original shelf space with a greater variety of groceries. Last month, the market also began selling beer and wine. Calling the customer response "tremendous," store owner David Kirby is expanding the operation into the empty storefront next door, more than doubling the market's capacity. Plans call for the new area to debut April 3, exactly one year after the Parker Street Market first opened.