Implements blueprint cfg-global-object
In glance.common.wsgi we have a paste_deploy_app() API which allows
a ConfigOpts instance to be passed the the applications and filters
constructed by PasteDeploy.
Now that we're using a global object, we don't need this anymore
Change-Id: I222d3c58308bc2f504cd802c0c8405d3baa2e49a