Condense multiple authorizers into a single one.

Reduces code duplication by creating a single authorizer and passing in
the action that should be checked against policy.

Change-Id: I33cfee8695ddfbba39038fbc608c6c74d258745f
import tools/flakes from oslo

Change-Id: Id6d99fe1fd39e8c061f591e9a82058aea9664674
Merge "Condense multiple authorizers into a single one."
Merge "import tools/flakes from oslo"