Added task to install apt packages idependent of the cinder-volume backend

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)

tasks/cinder_install_apt.yml

@@ -43,7 +43,19 @@
     - cinder-install
     - cinder-apt-packages
 
-- name: Install apt packages
+- name: Install apt packages common between different backends
+  apt:
+    pkg: "{{ item }}"
+    state: latest
+  register: install_packages
+  until: install_packages|success
+  retries: 5
+  delay: 2
+  with_items: "{{ cinder_volume_apt_packages }}"
+  when:
+    - inventory_hostname in groups['cinder_volume']
+
+- name: Install apt packages for LVM backend
   apt:
     pkg: "{{ item }}"
     state: latest

vars/ubuntu-14.04.yml

@@ -24,8 +24,10 @@ cinder_apt_packages:
   - zlib1g
   - zlibc
 
+cinder_volume_apt_packages:
+  - qemu-utils
+
 cinder_lvm_volume_apt_packages:
   - dmeventd
   - parted
-  - qemu-utils
   - tgt