Use banner images when adding new shows

[jamienicol]

In search results list display the show banner instead of the show name text, if available. Use the same trick with the transparent image as in the main shows list.

Should be pretty simple using Universal Image Loader. We should cache the images in memory but not on disk.

[jamienicol]

I tried this out and didn't like it: it takes a while to load the banners, and lots of shows that appear in search results don't have banners at all. so it looks a bit weird. I think the current behaviour is better.