add option for configuring lvm raid with multiple phsical disks

[graingert]

sudo bash lvm-on-luks sda 1 sdb 2 install \
    <size of swap  in G> \
    <size of /     in G or 0 for all remaining (no /home partition)> \
    [size of /home in G - if omitted and / size > 0: all remaining]

It could then ask you to choose raid config.

[rdkr]

Hi, happy to accept a PR to add functionality! Perhaps a flag to list physical disk partitions for the installation, e.g.

sudo bash lvm-on-luks install -r sda,1 -r sdb,2 ...

[graingert]

@rdkr yeah I'm asking because I don't know how to configure it myself ;)