Test List Vaults

This is based off PR #105 

Adds tests for List Vaults functionality.
The tests are fairly limited and not very deterministic.
The problem I encountered had to do with the Project Id and the fact that Delete Block/Delete Vault is not fully implemented.

Ideally, the List Vaults test would only be listing the vaults created during its setUp.
With the disk storage driver, this may be possible by making sure that each test uses a different, unique Project Id.
However, with the swift driver the Project Id is the Tenant Id. Since the clean up process for the tests is not working (Delete Files/Blocks/Vaults), the validation of the List Vaults functionality is restricted to:
* Check that, _at least_, all the vaults created in setUp are returned. Chances are that more vaults are going to get returned


Same issue as with test_list_multiple_vaults