Give YogaKitSample some love, Convert it to a Swift Project

Summary:
To date, our sample project was lacking. There is still a lot of work that can be done to improve, but, this is a step in the right direction.

Here are the changes in this commit:
1. The project is written in Swift.
2. Created new CollectionView (via [IGListKit](https://github.com/instagram/iglistkit)), making it very easy to add new examples.
3. New examples for basic layouts, and including/excluding layouts on the fly.

Here's a video!

![](https://media.giphy.com/media/l0ExcvTLa0ADdawRa/giphy.gif)
Closes https://github.com/facebook/yoga/pull/392

Reviewed By: emilsjolander

Differential Revision: D4550379

Pulled By: dshahidehpour

fbshipit-source-id: 64a07acf96c1887f1d2ad0c54971fcedb64334a0

YogaKit/YogaKitSample/YogaKitSample/AppDelegate.swift

@@ -0,0 +1,27 @@
+/**
+ * Copyright 2014-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the license found in the
+ * LICENSE-examples file in the root directory of this source tree.
+ */
+
+import Foundation
+import UIKit
+
+@UIApplicationMain
+class AppDelegate: UIResponder, UIApplicationDelegate {
+    var window: UIWindow?
+
+    func applicationDidFinishLaunching(_ application: UIApplication) {
+        self.window = UIWindow(frame: UIScreen.main.bounds)
+        if let window = self.window {
+            let navigationController = UINavigationController(rootViewController: ExamplesViewController())
+            navigationController.navigationBar.isTranslucent = false
+
+            window.rootViewController = navigationController
+            window.backgroundColor = .white
+            window.makeKeyAndVisible()
+        }
+    }
+}