Move the RDP challenge to it's own folder

[brookr]

Let's keep all the code for each challenge organized in their own folders.

[adrianhuebner]

@brookr While I am working on this, do you want the photo-album challenge renamed to pixon to match the challenge name?

[brookr]

Sounds good, yes, thank you. I'll need all the final URLs for each challenge to update the presenter slides.

[adrianhuebner]

Okay! I am working on moving everything right now and get those URLs to you!