Packages needed by cinder-volume, idependent of the backend, were installed
only when using a LVM backend. This change adds a new task and variable for
installing/declaring packages commonly used between different cinder-volume
backends.
Change-Id: Idd7fd6f8be710c106210ec5bdc3ecda1071fc913
Closes-Bug: #1580222
(cherry picked from commit 956683b908)