ceph-disk-udev: activate-journal

Trigger 'ceph-disk activate-journal' from the alt udev rules.

Signed-off-by: Sage Weil <sage@inktank.com>
udev: drop useless --mount argument to ceph-disk

It doesn't mean anything anymore; drop it.

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