Set owner of directory and keyrings according to owner of /var/lib/ceph.

Set owner of directory and keyrings according to owner of /var/lib/ceph.

If Ceph is running under a separate ceph user, it requires access
to various files under this user.
This patch tries to set owner of these files to the current owner
of base_dir (/var/lib/ceph).

If the ceph directory is owned by root, it expects old installation
and should work with old tools as well (avoids --setuser option).

Signed-off-by: Milan Broz <mbroz@redhat.com>