Add option to disable update check of Firefox Gnome Shell Integration
As GNOME Shell includes the "gnome-shell-extension-prefs" app which already checks for updates and shows a popup notification i suggest to add an option to disable the update checking of the Firefox Gnome Shell Integration add-on.
The "gnome-shell-extension-prefs" app correctly updates extension after next login, while the Firefox add-on updates the extension right away, which makes it to crash with red "ERROR" until next login or a manual restart of the GNOME Shell.
Also, this way the two popup notifications will become only one popup (that of "gnome-shell-extension-prefs" app).