Installation doesn't work with root on md raid

[nickles95]

If you try to install clear linux on an md raid partition, the installer refuses to continue because it thinks you have multiple CLR_ROOT partitions. You can get around this for raid 1 by creating the array in a degraded state with only one disk, installing on that, and then adding the other disks to the array afterwards, but it would be nice if the installer could do this without that workaround and this is necessary for raid 0/other levels of raid that fail to boot off of one disk.