Handle different-aspect game cover images

[aaronklaassen]

Launcher only supports 4:3 game cover images, and if someone uploads something else to the Network, it gets squished in the menu. Fixing it here is a better solution than fixing it API side: winnitron/winnitron_network#86

[mrmwiebe]

Cool. So basically it looks like you're thinkin the same as me here where it just crops the image to fit the current frame instead of squishing it right? I can look into that.

[aaronklaassen]

@mrmwiebe Or shows the whole image, ideally. I was going to crop it API-side just so that it didn't get squished, but showing the full image as-is in the menu would be the real fix.

I'm hesitant to crop because the cover images often have titles/text in them.