Replace parent class BaseAPITestCase by unittest.TestCase

[nixocio]

Few tests fail due to time-out that happening during the execution of tear down.
To reduce the number of calls to client.delete(ORPHANS_PATH), and try to reduce the number of failures. Replace the BaseAPITestCase by unittest.TestCase.

    @classmethod
    def tearDownClass(cls):
        """Delete all resources named by ``resources``."""
        client = api.Client(cls.cfg)
        for resource in cls.resources:
            client.delete(resource)
        client.delete(ORPHANS_PATH)

Basically, it will be necessary pass class by class, replace the parent class and do the necessary re-factors.

See also: #762

[Ichimonji10]

#1025 deprecated BaseAPITestCase.