This adds the CORS support middleware to Ceilometer, allowing a deployer
break the single-origin policy and access the API directly. Included
are Ceilometer's custom headers, so that anyone activating this
middleware does not have to explicitly enable them.
The paste.ini method of deploying the middleware was
chosen, because it needs to be able to annotate responses created
OpenStack CrossProject Spec:
OpenStack Cloud Admin Guide: