correct use of staging versus production Molecule scenarios

[cfm]

Towards #3:

1. Default to setting up a proper SecureDrop staging environment via make build-debs && make staging.
2. Offer "expert" instructions for using this setup as the basis for a production VM environment, installed from the preconfigured Tails domain.

Testing

1. [ ] terraform destroy if you already have an sd-staging box running.
2. [ ] terraform apply
3. [ ] Wait ~20 minutes for cloud-init to complete make build-debs && make staging.
4. [ ] Confirm that app-staging is fully configured by checking for the expected onion services:

   The web interfaces and SSH are available over Tor. A copy of the the Onion URLs for Source and Journalist Interfaces, as well as SSH access, are written to the Vagrant host’s install_files/ansible-base directory.

[eloquence]

Nit above aside (and using the new Tails image pulled in via #6), this worked perfectly for me. Here's the Tails VM accessing SI and JI set up via prod VMs (this server is now destroyed):

[cfm]

Thanks for testing, @eloquence!