Four years after settling on a site, a year after presenting its plan to the D.C. Zoning Commission and days after announcing a naming sponsorship deal, D.C. United finally has the go-ahead to build its new soccer stadium at Buzzard Point. The zoning panel gave final approval to the $300 million project Thursday. Team officials had hearings in November and December to hash out design issues(neighbors wanted more attention to retail and public spaces), parking and transportation and environmental concerns.