ceph-conf: make --show-config-value reflect daemon defaults

We want DAEMON defaults, but we don't want global_init to do anything else
daemonish like print a banner or mkdir /var/run/ceph.  This lets us use

 ceph-conf -n osd.0 --show-config-value log_file

to get the default, while

 ceph-conf -n osd.0 log_file

only reflects what is in the config file.

Signed-off-by: Sage Weil <sage@inktank.com>
ceph: fix ceph-conf call to get admin socket path for 'daemon <name> ...'

Signed-off-by: Sage Weil <sage@inktank.com>
init-radosgw: use radosgw --show-config-value to get config values

This way we get the correct default values, as reflected by radosgw
itself.

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