IDOC: Installation of zone information on purely offline systems, with automated registration for all

This is a gigantic pull request, encompassing much more than the changes in the title.  It has the following (SUPER AWESOME) dependencies:
* @arnaudbenard 's "frontend" branch (*new central server website*)
* @bcipolli 's "update_all" branch (in tandem with @rtibbles and @wangguan59 ), which introduces a new methods for communicating management command progress with front-end (browser) webpages, and uses it to do *software updates within a web interface*
* @bcipolli's "install_with_python" branch, using Python as our common install script.
And this branch implements all of the following:
* An "install wizard" (in tandem with @arnaudbenard , with inspiration from @wangguan59 ) for downloading different versions of KA Lite simple and easy.
* Packaging of zone information and signatures into a download, for offline installation and secure verification of the zip file during software updates
* Clickable scripts for launching an install (assumes python exists)
* Automated registration with the central server and the ability (with a software upgrade) to prove Zone membership without ever getting online

This pull request will take ages to annotate and sort through (259 file changes), but I wanted to start it now.  As I go through it, I will pull out some changes into independent pull requests, try to progressively merge dependencies in to release-idoc to remove them from appearing in this diff, and whatever other tricks I can find.  I will also be using this diff to comment code more thoroughly.  But as it stands... the code works!  Feel free to pull and try :)