Sync w/ updated power control interfaces

setPowerState/getPowerState methods are removed.
all properties are removed except PGood and State.
return value of forcePowerOff is changed to bool from int32

TestBy:
    Ipmi command and click buttons
Change-Id: I0b5e51cea959594acf04257c566893da6ffe7d26
Signed-off-by: Kuiying Wang <kuiying.wang@intel.com>
diff --git a/power-control/service-files/obmc-chassis-poweroff@.target b/power-control/service-files/obmc-chassis-poweroff@.target
index aa026cf..1bc0691 100644
--- a/power-control/service-files/obmc-chassis-poweroff@.target
+++ b/power-control/service-files/obmc-chassis-poweroff@.target
@@ -1,7 +1,7 @@
 [Unit]
 Description=Chassis%i (Power Off)
-Wants={SYSTEMD_DEFAULT_TARGET}
-After={SYSTEMD_DEFAULT_TARGET}
+Wants=obmc-standby.target
+After=obmc-standby.target
 Wants=mapper-wait@-xyz-openbmc_project-Chassis-Control-Power%i.service
 After=mapper-wait@-xyz-openbmc_project-Chassis-Control-Power%i.service
 Conflicts=obmc-chassis-poweron@%i.target