python/nuke.py - Doesn't consider where the raid volume to be nuked are.

As of the current version, nuke.py doesn't know or care where the raid volume is. It assume that `rd0` (translted into `/dev/rsd0c`) is the raid to get nuked.

either `install.py` should replace/add this dynamicly or `install.py` should set a unique label on the softraid crypto so that `nuke.py` can find it.
