Adds unit test for etc/nova/policy.json data

* Test live etc/nova/policy.json data
* Convert all actions in policy.json to admin-only actions
* Check that Policy auth exception is raised when all above actions are
  called using non-admin context

Change-Id: I1b97987f8e9e3bacc606385a56daad189cf6ce19
Closes-Bug: #1262325
Merge "Adds unit test for etc/nova/policy.json data"