Reorganizes blockstorage v1 testing infrastructure

* Removes empty integration package
* Fixes and expands blockstorage rehaviors, client and config.
* Renames volumes_api models to move them into the models namespace.

Change-Id: Ieba9f0b62c3abb15e2375b871e4f598ef4852f50
Merge "Reorganizes blockstorage v1 testing infrastructure"