add a 'get_spectrum' test
add a 'get_spectrum' test

allisony/pyspeckit,e-koch/pyspeckit,allisony/pyspeckit,pyspeckit/pyspeckit,jpinedaf/pyspeckit,low-sky/pyspeckit,low-sky/pyspeckit,pyspeckit/pyspeckit,e-koch/pyspeckit,vlas-sokolov/pyspeckit,jpinedaf/pyspeckit,keflavich/pyspeckit,vlas-sokolov/pyspeckit,keflavich/pyspeckit