Replace storage-url with service-catalog

Replacing storage url with a base 64 encoded service catalog obtained from identity.
This change is required in order to run the tests when the swift driver is used in deuce
@jc7998 - This might be part of the difference in my tests. My tests took the Dictionary Service Catalog Data returned by Keystone Client, did a JSON.dumps() on it, and then base64 encoded that.  The equivalent here would be:

```python
cls.service_catalog_b64 = base64.b64encode(cls.a_resp.json)
```

Since a_resp is a requests response object. Does that change resolve the issue described in CBDEUCE-208?