GconinjeWrapper: return raw instead of SI rates

the wrapper could be a bit more sophisticated and do the conversion
internally, but the new wells management code seems to ignore the
wrapper anyway, so there is no real point in investing time into that
(yet).
Merge pull request #122 from andlaus/gconinjecte_util_return_raw_instead_of_si_rates

GconinjeWrapper: return raw instead of SI rates