Allow Controller to manage volumes

Both the basic install guide, and full install guide describe having the controller run cinder-volume:

http://docs.openstack.org/grizzly/basic-install/apt/content/basic-install_controller.html#basic-install_controller-cinder
http://docs.openstack.org/grizzly/openstack-compute/install/apt/content/cinder-install.html

Right now this only supports an LVM backend, but could be extended in the future to support other volume backends.

Change-Id: I59eb05227b264dba164161e9d14502ba2af0f5c2
Merge "Allow Controller to manage volumes"