appDisplay: Rework indicators animation

Previously the animation was not entirely according to the mockup.
Now we are closer to the mockup.

The padding for the indicators are decremented, since we need that
to make the animation not too quick. As a drawback, maybe visually
is not as good as before, or the area to click dots is too much little.
Just make that change for now and test it widely, and we can change
that after.

https://bugzilla.gnome.org/show_bug.cgi?id=707565

data/theme/gnome-shell.css

@@ -941,7 +941,7 @@ StScrollBar StButton#vhandle:active {
 }
 
 .page-indicator {
-    padding: 15px 30px;
+    padding: 15px 20px;
 }
 
 .page-indicator .page-indicator-icon {