init-ceph, upstart: make crush update on osd start time out

If the monitor is not currently available, this crush update will block 
forever, preventing the OSD and (potentially) the rest of the system from 
starting up.  To avoid that, make it time out after a few seconds.  For most
cases, this will be fine, since usually the update is a no-op. However, we do
introduce the possibility that the osd will come up without its crush
position being updated.

For now, that seems less bad than before...

Works-around: #5612 Signed-off-by: Sage Weil <sage@inktank.com>