ceph.in, ceph_rest_api.py: import only used syms from ceph_argparse.py

This makes pyflakes/pylint happier and is better practice in general

Signed-off-by: Dan Mick <dan.mick@inktank.com>
cephtool/test.sh, rest/test.py: add tell command tests

Also add HTTP method to test.py output

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