Updating rally.conf.sample
Updating rally.conf.sample

If you clone rally and execute `tox -e genconfig`, you will see
that rally.conf.sample has some changes. It is because new release
of the oslo.log library has recently happened. Also rally.conf.sample
has some changes related to Sahara. So it looks like someone forgot to
execute `tox -e genconfig` before submitting the changes.

Change-Id: I582d3005d30705d34060e649d224808c419a2c69

group-policy/rally,vganapath/rally,eayunstack/rally,eonpatapon/rally,amit0701/rally,amit0701/rally,openstack/rally,gluke77/rally,vganapath/rally,gluke77/rally,group-policy/rally,amit0701/rally,gluke77/rally,eayunstack/rally,yeming233/rally,vganapath/rally,vganapath/rally,eonpatapon/rally,openstack/rally,openstack/rally,eayunstack/rally,group-policy/rally,yeming233/rally,gluke77/rally,openstack/rally