Fix cassandra vault stats, use dicts instead of tuples. 

This patch does a couple of things:

1) Fixes cassandra driver so it can run against a real cassandra instance. This was a regression caused by over overly liberal mocking framework.
2) Adds the ability to use dictionary-based arguments in our mocker.
3) Changes all arguments to be dictionary-based. 

Closes: CBDEUCE-154
Closes: CBDEUCE-141.


May be "internal" isn't the right verbage. It's basically an extension area for the drivers to add extra stuff that could be useful, like Swift's Last Modified Time (x-timestamp header).