Updated openstack/openstack
Project: openstack/tempest  f22b6cc7ba60b556e4dcb4b21c12fb516b6109fc

Access credential fields as attributes

Some tests access credentials attributes using dictionary
syntax (e.g. with get method); changed to use the Credentials
attribute directly.

Partially implements: bp multi-keystone-api-version-tests

Change-Id: Ic5b68af18d9a2dda581bdc1500d064e0ba732ec4