Fix zoom reloads image

When zooming in some browsers, like Safari on OS X and iOS, the image is
downloaded again before the zoom is applied.
This behavior has annoyed me for a long time, and is caused by how
cloneNode works in these browsers.
The solution removes the use of cloneNode for all browsers by instead
handing the carousel image element over to zoompanrotate, and then back
again.
Merge remote-tracking branch 'origin/fix-zoom-reloads-image' into test