Add backwards incompatability note to release notes for 0.17
Add backwards incompatability note to release notes for 0.17

KennethNielsen/SoCo,petteraas/SoCo,dajobe/SoCo,dajobe/SoCo,SoCo/SoCo,petteraas/SoCo,petteraas/SoCo,KennethNielsen/SoCo,SoCo/SoCo