Adding to the already crowded roster of mayoral candidates, Michael A. Brown, a lobbyist and the son of the late Clinton-era Commerce Secretary Ron Brown, today told the Washington Times that he would formally announce his candidacy for the city’s top job next month. His announcement will swell the ranks of mayoral hopefuls to five, including Council-members Adrian Fenty (D-Ward 4) and Vincent Orange (D-Ward 5), Council Chair Linda Cropp, and former Verizon executive Marie…