title: Transparent image background on WP7 HubTile
body: <p>I have a collection of HubTiles with user-selected images. If an image with transparency is selected, the HubTile's background color (PhoneAccentBrush) shows through. Is there a way to style just the photo background to Transparent without altering the animation backgrounds? (Although if the Title is displayed on a transparent background, that's acceptable, but I'd still like the flipside to use the accent color.)</p>
  
  <p>I've done some searching on styling the HubTile, but haven't been successful.</p>