Add volume backup commands

Change-Id: Iedccd329ff6fb3155eb29649cd0bc84cfc5ebedf
Implements: blueprint volume-backup
Remove explicit distribute depend.

Causes issues with the recent re-merge with setuptools. Advice from
upstream is to stop doing explicit depends.

Change-Id: Ic83dca8c17799335b76311d1d657adcd1dc94f01
Merge "Add volume backup commands"