[RFE] Add periodic power management health check..

Add periodic power management health check to detect/warn about link-down detection of power management

Feature pages:
http://www.ovirt.org/Features/PMHealthCheck
http://www.ovirt.org/index.php?title=Features/Design/DetailedPMHealthCheck

Change-Id: Ib1dfeab92a35793ebb421db8e3be94587dfe85e2
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1090800
Signed-off-by: Eli Mesika <emesika@redhat.com>