Fix: sbd-pacemaker: sync with pacemakerd for robustness

State query ping of pacemakerd prevents pacemakerd from
starting any sub-daemons (and thus services) if sbd can't
reach it via ipc. As a health-check get timestamp from
pacemakerd. On shudown fetch info about graceful
shutdown from pacemakerd.
Use new pacemakerd-api provided by pacemaker.