[rackspace] adding support for cloud block storage
Adding snapshotId to createVolume
[rackspace] cleaning up extension methods
Adding code docs for block storage
[Docs] docs for cloud block storagE
Update blockstorage.md for Snapshots
Update blockstorage.md for VolumeTypes
Adding quick links to Cloud Block Storage docs
Adding example for block storage with rackspace
[test] tests for cloud block storage
Adding doc updates for CBS