Call rally-manage with warning when openstack-rally-manage is used

Currently when openstack-rally-manage is used, args are passed through
to rally, not rally-manage. This patch fixes this situation.

Change-Id: I51fe14068f679d7f65fb4e518b8f55beca1c7d72
Closes-Bug: #1274068
Merge "Call rally-manage with warning when openstack-rally-manage is used"