This has been causing a lot of confusion for quite a while now and a lot
of users were surprised by this (some of them were even stuck in a
ENOSPC situation which they couldn't easily get out of).  The addition
of restriper gives users a clear choice between raid0 and drive concat
setup so there's absolutely no excuse for us to keep doing this.
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>