Adding chicken backgrounds, dressing room, and Chick Peek

I'm happy to present three features that have been requested a lot:

• You can now add image backgrounds to chicken cards. The upload button can be found on the chicken's profile.
• Dressing room: Now you can preview cosmetic items (filters and accessories) on chickens before buying them. Hopefully this averts some buyer's regret.
• Chick Peek: Preview the offspring possibilities of two chickens before committing to a nest! You can also use it on chickens you don't own, just in case you were thinking of buying one...

Under the hood there have been lots of changes with chicken thumbnail generation, the behaviour should remain the same, so if you notice anything being weird with chickens' images, that's probably because of those changes.