Add support for marginVertical and marginHorizontal

* implement margin as an array of values
* apply margins with the correct priority (e.g. left, horizontal, all)
* update transpiler & tests

src/java/tests/com/facebook/csslayout/LayoutCachingTest.java

@@ -114,7 +114,7 @@ public class LayoutCachingTest {
     root.calculateLayout();
     markLayoutAppliedForTree(root);
 
-    c1.setMarginLeft(10);
+    c1.setMargin(CSSNode.SPACING_LEFT, 10);
     root.calculateLayout();
 
     assertTrue(root.hasNewLayout());