Perhaps I'm still sun-drunk from the throwback sound of Pokey LaFarge this past weekend at Newport, but I'm jonesin' quite hard this Tuesday for a raw slice of singer/songwriter JD McPHERSON, who tonight hits T.T. The Bear's Place in Cambridge. With a sound perhaps more fitting for a rogue performance behind the venue in a back alley off Green Street, the Oklahoma-by-way-of-Chicago vintage rock rhythm and bluesman has been drawing some heavy Little Richard comparisons lately, as well as every four-star name-drop in rockabilly, roots, and old-school rock and roll.