Add auth support nailgun client

- Add keystone auth on Nailgun client initialization
- Add ability to refresh_token if it will expire
- If token is expired - new token will be requested

If no keystone is installed on master node - keystone
will raise exceptions.AuthorizationFailure which is handled,
and in this case NailgunClient will perform requests without auth

related to blueprint access-control-master-node

Change-Id: Ib7ff29e0a40e3075444c557f9c9e574b6ffa0071
Merge "Add auth support nailgun client"