Further hardening of build

[dragarcia]

This is to ensure that we are above and beyond in being compliant with the requirements of the AWS AMI and Digital Ocean marketplace.

Checklist

• Comply to Digital Ocean's security standards.
• Comply to AWS's security standards.
• Install Fail2ban. [Server][Additional]
• Install unattended-upgrades. [Server][Additional]
• Add in pgAudit [DB][Additional]