mds: set correct caps for new mds

Fixes: #5745
Signed-off-by: Sage Weil <sage@inktank.com>
fallback call to ceph for versions < dumpling

Signed-off-by: Alfredo Deza <alfredo@deza.pe>
update author and email attributes

Signed-off-by: Alfredo Deza <alfredo@deza.pe>