restapi : Update of power management via cli ignored(#959879)

Unable update power management fields via cli, but the
same works from web admin portal

This patch fixes all fields common between agents and the
power management model

Change-Id: Ifece398fd70a5928665c6f0c96a80450a6866f59
Bug-Url: https://bugzilla.redhat.com/959879
Signed-off-by: Ravi Nori <rnori@redhat.com>