Rename KeyBindingMode to ActionMode

The keybinding mode is no longer used exclusively for actions triggered
by keybindings, so reflect this by a more generic name.

https://bugzilla.gnome.org/show_bug.cgi?id=740237

js/ui/edgeDragAction.js

@@ -37,7 +37,7 @@ const EdgeDragAction = new Lang.Class({
         if (this.get_n_current_points() == 0)
             return false;
 
-        if (!(this._allowedModes & Main.keybindingMode))
+        if (!(this._allowedModes & Main.actionMode))
             return false;
 
         let [x, y] = this.get_press_coords(0);