rgw-admin: use 'get' instead of 'show' or info for geo stuff

These all output data that you can put back in via 'set', so they're
a 'get' rather than something else.

Signed-off-by: Greg Farnum <greg@inktank.com>
rgw-admin: add some of the newer flags and specify their use

Signed-off-by: Greg Farnum <greg@inktank.com>
Merge pull request #420 from gregsfortytwo/master

radosgw-admin help command naming and text improvements

Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>