Remove mostly unused complex infobox based notifications
Convert tweak_test to new TweakGroup API

* port to the new simpler notifications
Use CSS classes instead of selectors for theming
Remove some duplicate css by better using style classes
Attach CSS selectors to all tweaks and groups
tweak_group_window : Added the title bar buttons.
tweak_group_interface: Added the Shell Theme Tweak
Convert tweak_shell to new TweakGroup API