Fix broken test in fatiando.inversion doctests
Fix broken test in fatiando.inversion doctests

Some precision problem when printing a numpy array. Happens on 1.9 but not 1.10.
rafaelmds/fatiando,drandykass/fatiando,santis19/fatiando,victortxa/fatiando,fatiando/fatiando,fatiando/fatiando,mtb-za/fatiando,cmeessen/fatiando,mtb-za/fatiando,cmeessen/fatiando,rafaelmds/fatiando,drandykass/fatiando,victortxa/fatiando,santis19/fatiando