Set user/group of hello.txt to www-data

[philpep]

This patch break the full deployment because the file hello.txt doesn't exists. But it work on an already provisioned image (production).

Travis build: https://travis-ci.org/philpep/test-driven-infrastructure-example/builds/76951079
Jenkins build: https://jenkins.philpep.org/job/test-driven-infrastructure-example-pr/16/

TASK: [Set hello.txt owner/group to www-data] ********************************* 
failed: [default] => {"failed": true, "path": "/srv/website/hello.txt", "state": "absent"}
msg: file (/srv/website/hello.txt) is absent, cannot continue
changed: [production]