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/ViewControllers/BasicViewController.swift

@@ -0,0 +1,48 @@
+/**
+ * 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 UIKit
+import YogaKit
+
+final class BasicViewController: UIViewController {
+    override func viewDidLoad() {
+        let containerSize = self.view.bounds.size
+
+        let root = self.view!
+        root.backgroundColor = .white
+        root.yoga.isEnabled = true
+        root.yoga.width = containerSize.width
+        root.yoga.height = containerSize.height
+        root.yoga.alignItems = .center
+        root.yoga.justifyContent = .center
+
+        let child1 = UIView()
+        child1.backgroundColor = .blue
+        child1.yoga.isEnabled = true
+        child1.yoga.width = 100
+        child1.yoga.height = 10
+        child1.yoga.marginBottom = 25
+        root.addSubview(child1)
+
+        let child2 = UIView()
+        child2.yoga.isEnabled = true
+        child2.yoga.alignSelf = .flexEnd
+        child2.backgroundColor = .green
+        child2.frame = CGRect(x: 0, y: 0, width: 200, height: 100)
+        root.addSubview(child2)
+
+        let child3 = UIView()
+        child3.yoga.isEnabled = true
+        child3.yoga.alignSelf = .flexStart
+        child3.backgroundColor = .yellow
+        child3.frame = CGRect(x: 0, y: 0, width: 100, height: 100)
+        root.addSubview(child3)
+
+        root.yoga.applyLayout(preservingOrigin: true)
+    }
+}