Sync necessary modules from oslo incubator for worker service

Sync modelus: service, periodic_task and related dependencies
from oslo-incubator. Using the following command in oslo-incubator:

python update.py --base rally --dest-dir ../rally --modules \
periodic_task,service

Change-Id: I0b8278404d53a91add7a8cf3876121aad1e497c2
Merge "Sync necessary modules from oslo incubator for worker service"