Better --check compatibility for ceph-rgw role

Carefully chosen "always_run: true" parameters for read-only tasks that
register variables. This enables --check runs (at least on deployed
clusters).

roles/ceph-rgw/tasks/start_radosgw.yml

@@ -4,6 +4,7 @@
   register: rgwstatus
   changed_when: false
   failed_when: false
+  always_run: true
 
 - name: start rgw
   command: /etc/init.d/radosgw start