mon: make 'osd crush link ...' idempotent

We fixed move in f5ba0fbbe73e11418634bc95e1fc36d17edccf37 but missed this
one.

Signed-off-by: Sage Weil <sage@inktank.com>
mon: ensure 'osd crush rule ...' commands are idempotent

Ensure that we return 0 for these cases.

Signed-off-by: Sage Weil <sage@inktank.com>
Merge pull request #224 from ceph/wip-mon-crush

Wip mon crush

Reviewed-by: Dan Mick <dan.mick@inktank.com>