Update to Swift 2

[ryanmasondavies]

Have gone through the basic migration process to support Swift 2, but haven't fully embraced the improvements. Code should be refactored to use newer syntax such as guard, defer, where needed, and use struct and protocols in place of classes where possible.

[digitallysavvy]

I just tried your current build on an iPhone 6 using iOS 9.3 and the entire camera image is pixilated, not just the face. I created a new pull request with updated code to work with Swift 2.3. It uses the black circle over the face.

[ryanmasondavies]

Thanks! I've replied to your pull request. It looks like you haven't got the latest changes in the repo – if you can pull and merge the master branch with your pull request, I'd be happy to accept it. 👍