Python-2.6 compatibility for tests/test_keyring.py

TestCase.setUpClass() and unittest.SkipTest are features added in 2.7.
Calling super(KeyringTest, cls).setUpClass() could have never worked
since tests.utils.TestCase doesn't implement that (class) method.

Change-Id: Ifbb0465be24fd13ad68d52c0d7fa4c5090d0f694
Implements v3 auth client.

Added support for domain scoping.

Enhancement on AccessInfo to support reading v2/v3 token information.

Enhancement on ServiceCatalog for reading/filtering v2/v3 service
catalog information.

Change-Id: Ibb678b9933d3673e37d0fba857a152a3c5d2b4f4
Merge "Python-2.6 compatibility for tests/test_keyring.py"