Additional fixes:
- Fix AboutPlugin exception if one of the plugin is failing to load
- The interface wasn't updated on anonymous user language/theme change
  Anonymous plugin get_user() method need to return a newly created object,
  so that its configuration stay is up-to-date.
- Update from prelude-ids.org to prelude-siem.org
- Hide filter popups in AlertListing template
  to avoid flickering caused to CSS loading