mds/rgw: created /var/lib/ceph/[mds|rgw]/<mds>/keyring owned by root and world readable

For mds and rgw:
From Jewel on it should be owned by ceph:ceph and generally it should be mode 600.

I believe this is also wrong in latest ceph-deploy.

regarding this bug in ceph-deploy a repost from #ceph irc channel
hoonetorg: There was a bug raised for that recently, I think. Version 1.5.23 ish.
So they are aware of that.

[oms4suse]

@hoonetorg thanks for this bug report, I guess this will be my next patch :)

[oms4suse]

Fixed in this PR #24