Jeremiah Ellison, the radical son of Minnesota attorney general Keith Ellison and a Minneapolis city councilman, is rankling some of his Democratic colleagues after jetting off to Cambridge, Mass., for a full-time fellowship at Harvard University, but is insisting on keeping his job and six-figure salary. The younger Ellison was awarded Harvard's Loeb fellowship , in which fellows "agree to step away from any significant roles with their employers and other employment responsibilities; to