tutorial post playbook - ignore errors getting docker logs

Something is failing in here, but we can't see it because the output
is all sent to logs which then aren't collected if the task fails.
Ignore errors here, that way we should get whatever logs we can.

Change-Id: Iba90c5b0b084b8740c40cb4e611eb7d46a83834e

playbooks/tutorial/post.yaml

@@ -7,6 +7,7 @@
         mode: 0755
     - name: Save docker log files
       become: true
+      ignore_errors: yes
       shell: |
         docker logs zuultutorial_gerrit_1 > {{ ansible_user_dir }}/logs/gerrit.log 2>&1
         docker logs zuultutorial_gerritconfig_1 > {{ ansible_user_dir }}/logs/gerritconfig.log 2>&1