Give user the ability to select which fanart to display

```
Just add a button to the series info panel where the user can select which 
poster/banner/background to display from the UI.  Will probably need a little 
re-plumbing in the image caching, but shouldn't be to bad.
```

Original issue reported on code.google.com by `zadigian` on 12 Apr 2011 at 11:05
