Add automated tests for Upgrade Status module

I have a feeling to get the module actually working it'd be really helpful to have automated tests for it.

Update Manager has some nice dummy tests we could probably copypasta a lot from here.

Brainstorm of test cases:

• Module that has no 8.x release. Example: most of them. :P~
• Module that has a stable release for 8.0. Example: https://drupal.org/project/bad_judgement
• Module that has a 8.x dev snapshot only. Example: https://drupal.org/project/libraries
• Module that has a 8.x alpha release. Example: https://drupal.org/project/ds
• Module that has a 8.x beta release. Example: https://drupal.org/project/honeypot
• Module that has a 8.x rc release. Example: https://drupal.org/project/fb_likebox
• Module that was moved into core, no caveats. Example: https://drupal.org/project/views (this one also has a dev snapshot so that might be interesting.)
• Module that was moved into core partially, and has some caveats. Example: https://drupal.org/project/date
• Module that was moved into core with a name switch. Example: https://drupal.org/project/navbar