Security #1: Don't share it all

By default, the entire project directory is shared on all Vagrant hosts. In this case, that would include the entire PKI.

Added a specific shared/ directoy and instructed Vagrant to use that one.
Security #2: Firewall!
Salt modules: the firewall
Security #3: SSH configuration
Security #4: Unattended upgrades
Salt modules: firewall fix
Security #5: Privileged users
Restructuring the salt tree
Using pillar data to configure users and minions
Merge branch 'feature/security-essentials' into develop