Code review comment for lp:~wesley-wiedenmeier/curtin/1562249

I fixed the issue with cciss partition knames and added a unittest. There is a new version of curtin building in my ppa right now, and I will have that copied over into trusty/xenial/yakkety soon. I think that this is the last place where the differences between cciss naming and regular naming will be an issue, so hopefully this version should install correctly.