Create objects for running PSUs

On service startup, create activation and version objects for running
PSUs, and set related active, functional associations.

If multiple PSUs are running with the same software version, they share
the same DBus object, and the object will be associated to multiple PSU
inventories.

Tested: Verify the software objects are created on Witherspoon, and the
        active, functional associations are created.

Signed-off-by: Lei YU <mine260309@gmail.com>
Change-Id: Ia8372aba8299818baccfdf37e98fdbc99f747b7c
8 files changed