Show all the skin's elements along with the preview images

[Comentarinformal]

This might be hard, since I'd need an up-to-date list of all the files in a normal skin, compare against them, (for each gamemode!), and then copy&paste all the ones that apply on a comp. generated image; all of this fast, so the user doesn't get too bored waiting... This might probably need a lot of resources (compared to right now), so I'm keeping it until we move to Chicago.

[Comentarinformal]

Well, I just need to implement it with the current uploader, change little parts here and there, and it should be done! It's already implemented on (dev branch) skin page. Tidied it up a bit, too.

[Comentarinformal]

Now live!