Photo SlideShow major changes
* async request for image metadata ( non-blocking )
   - allows us to cancel pending requests if user hold/presses next/prev buttons
   - fixes complicated users request, cancel prior request logic
   - fixes showing the next/prev image after user holds down next/prev or presses it quickly
* Shuffle/Unshuffle dialog changed to match standard ( shuffle: on / shuffle: off -- keep dialog open )
* Show "loading image..." if first image fails to download