The purpose of this patch set is to provide the end users with
the following functionalities:
1. Extend the size of the specified volume.
2. Set attachment metadata of the specified volume.
3. Update state of the specified volume.
4. Set image metadata of the specified volume.
5. Unset image metadata of the specified volume.
6. Show image metadata of the specified volume.
Change-Id: Ie9e4ca15a412c89a3c44f1b8526e6597eddf762c