ceph-monstore-tool: dump-keys command

Signed-off-by: Sage Weil <sage@inktank.com>
ceph-monstore-tool: compact command

Signed-off-by: Sage Weil <sage@inktank.com>
ceph-monstore-tool: be more verbose when replaying a trace

Signed-off-by: Sage Weil <sage@inktank.com>
rbd: prevent import of a dir

Fixes: #2865
Signed-off-by: Sage Weil <sage@inktank.com>