Add / change some pngs

Delete buttons:

 - "ic_notify_clear_normal"
 - "ic_notify_quicksettings_normal"

Change buttons to match better with other themed buttons:

 - "ic_notify_clear_pressed"
 - "ic_notify_quicksettings_pressed"

Add buttons:

 - "ic_notify_open_pressed"
 - "ic_notify_settings_pressed"