ceph-disk: use partition type UUIDs, and blkid

Use blkid to give us the GPT partition type.  This lets us distinguish
between dmcrypt and non-dmcrypt partitions.  Fake it if blkid doesn't
give us what we want and try with sgdisk.  This isn't perfect (it can't
tell between dmcrypt and not dmcrypt), but such is life, and we are better
off than before.

Signed-off-by: Sage Weil <sage@redhat.com>
ceph-disk: move fs mount probe into a helper

Signed-off-by: Sage Weil <sage@redhat.com>
ceph-disk: display information about dmcrypted data and journal volumes

Signed-off-by: Sage Weil <sage@redhat.com>