Fix naming convetion:

- "Layout node" is changed to "layout spec".
- Update tests.
- Update Kittens sample.

AsyncDisplayKit/Layout/ASRatioLayoutSpec.h

@@ -0,0 +1,36 @@
+/*
+ *  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.
+ *
+ */
+
+#import <AsyncDisplayKit/ASLayoutSpec.h>
+#import <AsyncDisplayKit/ASLayoutable.h>
+
+/**
+ Ratio layout spec
+ For when the content should respect a certain inherent ratio but can be scaled (think photos or videos)
+ The ratio passed is the ratio of height / width you expect
+
+ For a ratio 0.5, the spec will have a flat rectangle shape
+  _ _ _ _
+ |       |
+ |_ _ _ _|
+
+ For a ratio 2.0, the spec will be twice as tall as it is wide
+  _ _
+ |   |
+ |   |
+ |   |
+ |_ _|
+
+ **/
+@interface ASRatioLayoutSpec : ASLayoutSpec
+
++ (instancetype)newWithRatio:(CGFloat)ratio child:(id<ASLayoutable>)child;
+
+@end