DSA keys are being deprecated: http://www.openssh.com/legacy.html
drop.ceph.com will continue to allow the old DSA key but eventually,
users submitting logs using ceph-post-file will run into issues when
OpenSSH completely drops support for the algorithm.
Fixes: http://tracker.ceph.com/issues/14267
Signed-off-by: David Galloway <dgallowa@redhat.com>