Use Resource class from Oslo

Most methods of Resource class from keystoneclient are similar to methods
from common code.
In the process of unification of the clients code we should
reuse common functionality from Oslo.

Related to blueprint common-client-library-2

Change-Id: I5858eec1596a6921dcf49dfcefb7abd4387de73b
Test query-string for list actions with filter arguments

httpretty.register_uri only matches the path, not the query
string, so the test_list will pass even if the query string
passed by the manager doesn't match that passed as part of
expected_path.

So add a test for the query component of all list requests,
and a way to override the expected query, which is needed in
the trusts list filter tests where the query string doesn't
exactly match the kwargs passed to the client API.

Change-Id: I290b73bbbdac88487c225063fd3775ab7dd8bb89
Replace assertEqual(None, *) with assertIsNone in tests

Replace assertEqual(None, *) with assertIsNone in tests to have
more clear messages in case of failure.

Change-Id: I8ba72d345ad00f5cde8696ab82c31606ca82a13f
Merge "Use Resource class from Oslo"
Merge "Test query-string for list actions with filter arguments"
Merge "Replace assertEqual(None, *) with assertIsNone in tests"