Added tokenless auth headers to CORS middleware
Added tokenless auth headers to CORS middleware

This adds the headers necessary for tokenless auth to the latent
configuration parameters of oslo's CORS middleware. It ensures
that an operator does not have to know additional magic
configuration properties just to make auth work.

Change-Id: Ibac1937e97b65afca337b42837253a4a3dec6a40

mahak/keystone,klmitch/keystone,mahak/keystone,klmitch/keystone,openstack/keystone,cernops/keystone,dims/keystone,rajalokan/keystone,rajalokan/keystone,cernops/keystone,ilay09/keystone,ilay09/keystone,dims/keystone,rajalokan/keystone,ilay09/keystone,openstack/keystone,openstack/keystone,himanshu-setia/keystone,mahak/keystone,himanshu-setia/keystone