[pve-devel] use our own format for LXC containers

[Dietmar Maurer]

> I wonder if we could use something generic like
> 
> hdd0: local:101/subvol-101-disk-1.raw,size=4,mp=/

I prefer 'rootfs' instead, because 'rootfs' has fixed mp '/', and is a required
option.

> hdd1: faststore:101/subvol-101-disk-1.raw,size=1,mp=/mnt/faststore
> hdd2: slowbigstore:101/subvol-101-disk-1.raw,size=1024,mp=/mnt/slowbigstore

those are optional, and have a montpoint.