Fix to force cursor update after animation completes

Hopefully this fixes fat#19

This fix changes the body's cursor style during animation, which
forces the zoomed image's cursor style to apply.

Chromium has issues updating the cursor while the cursor is idle.
See [Chromium Issue 26723: Mouse cursor doesn't change when mouse-idling][1].

  [1]: https://code.google.com/p/chromium/issues/detail?id=26723

css/zoom.css

@@ -35,3 +35,11 @@ img.zoom-img {
   filter: "alpha(opacity=100)";
   opacity: 1;
 }
+.zoom-overlay-open {
+  cursor: pointer;
+  cursor: -webkit-zoom-out;
+  cursor: -moz-zoom-out;
+}
+.zoom-overlay-transitioning {
+  cursor: default;
+}