[ReactNative] LayoutAnimation brevity

Summary:
@public

Less verbose - now can just do `LayoutAnimation.easeInEaseOut()` instead of
`LayoutAnimation.configureNext(LayoutAnimation.Presets.easeInEaseOut)`

Test Plan: D2171336, play with AdsManager pickers.

Libraries/Animation/LayoutAnimation.js

@@ -114,4 +114,10 @@ var LayoutAnimation = {
   }
 };
 
+for (var key in LayoutAnimation.Presets) {
+  LayoutAnimation[key] = LayoutAnimation.configureNext.bind(
+    null, LayoutAnimation.Presets[key]
+  );
+}
+
 module.exports = LayoutAnimation;