Add occ-dbus object

- The intent behind this commit is to add APIs for dynamically
  createing D-Bus objects.

- When temperature values such as DIMM or Core are monitored, D-Bus
  objects need to be dynamically created and the corresponding
  attribute values updated. If the object path exists, only the
  attribute value needs to be updated.

- Currently supports Sensor and OperationalStatus interfaces.

- Also, added Unit Test to occ_dbus file.

Tested: built openpower-occ-control successfully and UTest pass.

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I1eac918d6a7a04d6b72b4e68fff868b04dde9c28
5 files changed