debian: add support

This patch adds support for this role to be able to deploy on
Debian Stretch.

Change-Id: I1058238e2467cc257ec48ba84fb89995079e9be7
Needed-By: I9a92b73c419a0dc1cca40dacfef75de61a61db94

tasks/drivers/kvm/nova_compute_kvm.yml

@@ -133,7 +133,7 @@
     regexp: "^KSM_ENABLED=*"
     backup: yes
   when:
-    - ansible_pkg_mgr == 'apt'
+    - ansible_distribution == 'Ubuntu'
   notify: Restart libvirt-bin
   tags:
     - nova-config

vars/debian.yml

@@ -70,7 +70,7 @@ nova_compute_kvm_distro_packages:
   - bridge-utils
   - genisoimage
   - kpartx
-  - libvirt-bin
+  - "{{ (ansible_distribution == 'Debian') | ternary('libvirt-daemon-system', 'libvirt-bin') }}"
   - open-iscsi
   - python-guestfs
   - python3-guestfs