[NbtkScrollButton] Emit signal by id instead of by name.
[NbtkScrollButton] Emit signal by id instead of by name.

clutter-project/mx,jonnylamb/mx,pwithnall/mx,jonnylamb/mx,jonnylamb/mx,pwithnall/mx,jonnylamb/mx,pwithnall/mx,pwithnall/mx,clutter-project/mx,clutter-project/mx,clutter-project/mx