SERIES PREMIERE: If you were a Downton Abbey fan (and if not, why not?), you probably enjoyed the brittle Britishness of Lady Mary, played so flintily, but ultimately so flirtingly, by Michelle Dockery. Well, for her new series, Dockery throws all that British period costume stuff aside, and plays a very modern role, in modern dress and times: a Southern ex-con who still works as a con woman. In the first 20 minutes alone, she gets to play a blonde (shown here), a brunette, and a redhead &