A few tweaks to implementation of the game list screen.

-Show file sizes as "X.XX GiB" like what is done on the desktop.

-Have NoBanner.png be displayed as a drawable resource - previously it was placed in /assets/, being loaded as a raw file, and then read as a filestream. Android does all of this for free if we call it a resource.

-That weird launcher activity (what's the deal with that, btw?) was set to force landscape orientation, which was causing weird rotation events on launch, even if the device already was in landscape. I can't think of why this would be necessary (though I also don't know why it's necessary to have that separate activity in the first place) so I've undone that.

End result on Nexus 10:
![screenshot_2014-07-04-15-46-44](https://cloud.githubusercontent.com/assets/1912034/3484801/7b3c2e34-03b6-11e4-835a-cb5a40c8796d.png)


I don't like to omit brackets (I'm prone to goto-fail-esque errors whenever I do that) but I can make the change if it violates our code style.