Randomize letsencrypt cron job

Signed-off-by: Mattia Rizzolo <mapreri@ubuntu.com>

roles/ssl-keys/tasks/letsencrypt.yml

@@ -22,7 +22,9 @@
     cron_file: ssl
     state: present
     user: ssl-keys
-    special_time: weekly
+    minute: 23
+    hour: 2
+    dow: 0
     env: "{{ item.env }}"
     name: "{{ item.name }}"
     job: "{{ item.job }}"
@@ -32,7 +34,7 @@
       job: root
     - env: false
       name: ssl-keys
-      job: chronic dehydrated -c
+      job: "perl -e 'sleep int(rand(3600))' && chronic dehydrated -c"
 
 - name: Install the apache configuration
   apt: name=dehydrated-apache2 state=present