Fixed blockstorage package structure to match other products.

* Moved versioning to inside the volumes_api package.
* Movied blockstorage config from volumes_api to the
  blockstorage package.
* Modified old imports to reflect new package structure.

Change-Id: I4dc97ef8b49fa1eb299b8c3b70eae3d3316caa03
Merge "Fixed blockstorage package structure to match other products."