Really use the hostname, otherwise ambiguous

"hostname" can return either the hostname or the fqdn depending on
configuration.
This refers to the issue http://tracker.ceph.com/issues/6706

Signed-off-by: David Moreau Simard <dmsimard@iweb.com>
Merge pull request #801 from dmsimard/wip_6706

Really use the hostname, otherwise ambiguous

Reviewed-by: Sage Weil <sage@inktank.com>