Update etc/keystone.conf.sample
Update etc/keystone.conf.sample

If we generate keystone.conf using "tox -e genconfig",
some options are different from the sample file.
So update it.

Change-Id: I7f20338d2fab60f692dc58ca731a6a56279224fe

mahak/keystone,mahak/keystone,openstack/keystone,ilay09/keystone,openstack/keystone,mahak/keystone,ilay09/keystone,ilay09/keystone,openstack/keystone,rajalokan/keystone,rajalokan/keystone,rajalokan/keystone