Make spinner spin
Make spinner spin

This makes the spinner spin (by starting it) and uses the
new GdMainToolbar.add_widget() method to avoid putting the
spinner in a button, as that makes the spinning animation
look weird (themed as in a depressed button).

https://bugzilla.gnome.org/show_bug.cgi?id=684858

vbenes/gnome-boxes,vbenes/gnome-boxes