Blockstorage test refactor and buildout

* Fixes and expands blockstorage test fixtures
* Adds working auth integration to blockstorage.
* Adds blockstorage data driven test dataset list generator class.
* Adds volume type dataset list generator.
* Adds volume and snapshot datadriven smoketests.
* Updates os-volume_attachments api integration to reflect upstream
  changes.
* Updates compute volume integration tests to reflact upstream changes.
* Fixes broken snapshot smoke tests.

Change-Id: I9eb4731aa4f76068d7e58a4046d5c1459d7c1547