[Layout Transition] Add default fade in / out layout transition (#2052)

* Add default fade in / out layout transition

* Add example for layout transition

* Update for recent layout transition API changes

* To be able to do a layoutTransition the node needs to be loaded

* Rename layoutTransitionDuration to defaultLayoutTransitionDuration

* Expose default layout transition duration delay and options

* Use `UIViewAnimationOptionBeginFromCurrentState` for initial defaultLayoutTransitionOptions

examples/ASDKLayoutTransition/Sample/AppDelegate.m

@@ -0,0 +1,33 @@
+//
+//  AppDelegate.m
+//  Sample
+//
+//  Copyright (c) 2014-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under the BSD-style license found in the
+//  LICENSE file in the root directory of this source tree. An additional grant
+//  of patent rights can be found in the PATENTS file in the same directory.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+//  FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+//  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+//  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+//
+
+#import "AppDelegate.h"
+
+#import "ViewController.h"
+
+@implementation AppDelegate
+
+- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
+{
+  self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
+  self.window.backgroundColor = [UIColor whiteColor];
+  self.window.rootViewController = [[ViewController alloc] init];
+  [self.window makeKeyAndVisible];
+  return YES;
+}
+
+@end