enable unattended security updates in ubuntu

[theskumar]

During anisble setup make sure unattended upgrade via cron

Resources:

• https://help.ubuntu.com/16.04/serverguide/automatic-updates.html
• https://github.com/jcalazan/ansible-django-stack#security
• http://www.codelitt.com/blog/my-first-10-minutes-on-a-server-primer-for-securing-ubuntu/

[CuriousLearner]

We can add the security Ansible role from this repo: https://github.com/jcalazan/ansible-django-stack/tree/master/roles/security

Thoughts?

[theskumar]

yeah. that sounds good to me. https://github.com/jcalazan/ansible-django-stack/blob/master/roles/security/tasks/setup_unattended_upgrades.yml for this PR.