Remove admin auth when getting the list of Neutron API extensions.

Currently _refresh_neutron_extensions_cache() always authenticates
with Neutron using the configured Neutron admin credentials because
it doesn't have access to the calling context.  But it's actually
always called when a valid context exists, and the call to get the
list of extensions is not itself an admin operation.  By passing
the context down we can avoid this additional authentication step.

Change-Id: I9e7d9c5e424a6b39c8f8ee1c79f5fd8f48ad81a2
Closes-Bug: 1250850
Make baremetal driver use Flavor object instead of VirtAPI

This makes the baremetal driver use the Flavor object instead of
getting that information through the VirtAPI/conductor call.

Related to blueprint compute-manager-objects

Change-Id: I1cbc3fc77bbbcaa3c194f12814893c5937fb6e96
Make compute manager use Flavor object

This makes compute manager use the Flavor objects instead of a
raw conductor API to get information about flavors during resize.

Related to blueprint compute-manager-objects

Change-Id: Ieb56b754eb5a4824fc69093897bdff25ab020883
Make resource_tracker use Flavor object

This makes the resource_tracker use the Flavor object for getting
information about an instance's flavor instead of a raw call to
conductor.

Related to blueprint compute-manager-objects

Change-Id: Ida93eeed9b8f8f5da267cff6a6b38f6661479b36
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 "Remove admin auth when getting the list of Neutron API extensions."
Merge "Adds unit test for etc/nova/policy.json data"
Merge "Make baremetal driver use Flavor object instead of VirtAPI"
Merge "Make compute manager use Flavor object"
Merge "Make resource_tracker use Flavor object"