The ghosts of mayors past and present are haunting every step of the District’s Ward 8 Council race.Mayor Muriel E. Bowser (D) showed up at a barbecue for LaRuby May ahead of a straw poll earlier this month; former mayor Vincent C. Gray appears side by side with his endorsed candidate, Sheila Bunn, on fliers; and just about everyone invokes the name of the late D.C.