Create a `securedrop-admin` debian package

[micahflee]

This issue should do the following:

• Add a build-debs-admin to ./builder to make a new securedrop-admin package
• The package should include:
  • The install_files/ansible-base source tree
  • Admin dependencies, probably by vendoring a virtual env?
  • A securedrop-admin command installed in /usr/bin
  • A file with the current securedrop version string (since we won’t have the full securedrop repo on disk anymore, we need a way to check if we’re up-to-date)
• We need to do the following refactoring for this to work:
  • Refactor check_for_updates to use the github API to check git tags, rather that the output of git tag in a git branch
  • Delete update because updates will be handled via apt instead
  • Delete the whole ./securedrop-admin setup stuff that installs debian packages and pip dependencies, because this will just be included in the package
• Update documentation for how to install this package in Tails, similar to the Dangerzone docs
• Package dependencies should include at least: python3, tor, netcat-openbsd

[legoktm]

I pushed some scaffolding to an admin-deb branch: 3b5754f. It should create a Debian package, set up the virtualenv,

There are some TODOs listed in the commit message; I think the main big thing to figure out is the filesystem layout, like where install_files/ansible-base should be installed.

Also if you create a debian/links file (docs), you can create /usr/bin/securedrop-admin as a symlink to the venv-installed version.

I started setting up the builder/ stuff but hit my timebox limit, so I didn't finish. I think you should be able to copy/paste and adjust the existing stuff though. (Also that means I didn't test the packaging yet).