Public/Private Bastion Parameters

[cchurch]

Implement additional comments from here: #61 (comment)

• The user would be given the option of having the "private" subnets be truly private, or simply marked private but still publicly routable
• If they chose "private", create a bastion host by default
• If they chose "private", give them the option of (a) creating a NAT gateway or (b) routing traffic through the bastion (e.g., if it were configured to run pfSense or another firewall); see: https://github.com/caktus/fabulaws/pull/80/files#diff-4782546e1e3efa690871d073242d463b