This commit adds most of the backend needed to implement the download
pages. It implements:

- Automatic fetch of the .iso's md5s the first time the application is
  started (and when they change), so they're available to show in the
  "Thank you" page

- Automatic fetch of the list of official mirrors for Ubuntu from the
  Launchpad API

- Download URL generation, which randomizes between mirrors to avoid
  overloading one of them

Nuovo tema

See merge request !14

This commit generates a new secret key (used by Flask to sign cookies
and other stuff) the first time an instance is started within a data
directory. The key is not regenerated the next startups, to avoid
invalidating stuff.

Running them under a PTY makes the build log a big bad mess

Fixes #5

This file defines how managetests will build and run the instance.

Really old setuptools versions don't include images in the resulting
packages.

Let's try to keep the same URLs as before.

Boring md files

Aggiungi file MD per gli autori e su come contribuire

See merge request !2