Use the use_systemd fact when starting rbd

Signed-off-by: Andrew Schoen <aschoen@redhat.com>

roles/ceph-rbd-mirror/tasks/start_rbd_mirror.yml

@@ -1,20 +1,20 @@
 ---
-- name: start and add that the rbd mirror service to the init sequence (ubuntu)
+- name: start and add that the rbd mirror service to the init sequence (upstart)
   command: initctl emit ceph-rbd-mirror cluster={{ cluster }} id={{ ansible_hostname }}
   changed_when: false
   failed_when: false
-  when: ansible_distribution == "Ubuntu"
+  when: not use_systemd
 
 # NOTE (leseb): somehow the service ansible module is messing things up
 # as a safety measure we run the raw command
-- name: start and add that the rbd mirror service to the init sequence
+- name: start and add that the rbd mirror service to the init sequence (systemd before infernalis)
   command: service ceph start ceph-rbd-mirror
   changed_when: false
   when:
-    ansible_distribution != "Ubuntu" and
+    use_systemd and
     is_before_infernalis
 
-- name: enable systemd unit file for the rbd mirror service (for or after infernalis)
+- name: enable systemd unit file for the rbd mirror service (systemd after hammer)
   file:
     src: /usr/lib/systemd/system/ceph-rbd-mirror@.service
     dest: "/etc/systemd/system/multi-user.target.wants/ceph-rbd-mirror@{{ ceph_rbd_mirror_local_user }}.service"
@@ -22,15 +22,15 @@
   changed_when: false
   failed_when: false
   when:
-    ansible_distribution != "Ubuntu" and
+    use_systemd and
     is_after_hammer
 
-- name: start and add that the rbd mirror service to the init sequence (for or after infernalis)
+- name: start and add that the rbd mirror service to the init sequence (systemd after hammer)
   service:
       name: "ceph-rbd-mirror@{{ ceph_rbd_mirror_local_user }}"
       state: started
       enabled: yes
   changed_when: false
   when:
-    ansible_distribution != "Ubuntu" and
+    use_systemd and
     is_after_hammer