Add policy checks to API

Adds ability for deploy-time auth checks to allow/disallow
functionality, in line with other openstack projects.

Includes update of code in openstack/common, which is why the
patchset is so large. oslo-incubator changeset is May 27th
caed79d8239679cb74476bb0d9e5011b4fcc39da.

Implements blueprint policy-checks-in-api

Change-Id: I67a431dcc74f0a77ed48b7a489136d5008773cea
Merge "Add policy checks to API"