ceph.in/ceph_argparse.py: move find_cmd_target() to ceph_argparse.py

Signed-off-by: Dan Mick <dan.mick@inktank.com>
ceph_rest_api.py: remove unused imports

Signed-off-by: Dan Mick <dan.mick@inktank.com>
OSD: provide newer command descs with module/perm/avail

Signed-off-by: Dan Mick <dan.mick@inktank.com>