Cocoa bindings to manage view state
Play a sample stream using AVFoundation

Seems like a little bit too much hassle, and asset always returns zero
tracks for [asset tracksWithMediaType:AVMediaTypeVideo]. However,
ignoring this, we can simply play the stream nonetheless.

Next things:
1. Stream live preview from a real camera
2. Update view state (toggle recording/stop, cam info…)
3. File browser and import/download