added kb to units
added kb to units

bsipocz/pyspeckit,jpinedaf/pyspeckit,vlas-sokolov/pyspeckit,dinossimpson/pyspeckit,low-sky/pyspeckit,allisony/pyspeckit,keflavich/pyspeckit,e-koch/pyspeckit,allisony/pyspeckit,vlas-sokolov/pyspeckit,keflavich/pyspeckit-obsolete,dinossimpson/pyspeckit,mikelum/pyspeckit,mikelum/pyspeckit,pyspeckit/pyspeckit,low-sky/pyspeckit,e-koch/pyspeckit,keflavich/pyspeckit,pyspeckit/pyspeckit,bsipocz/pyspeckit,jpinedaf/pyspeckit