Allow transition xml resources

Summary: https://developer.android.com/reference/android/transition/Transition documents that `transition` is an allowed resource folder.

Reviewed By: styurin

fbshipit-source-id: 784d7c22a4

Author: asp2insp

src/com/facebook/buck/android/ResourceFilters.java

@@ -58,7 +58,11 @@ private ResourceFilters() {}
           "xml",
           // "interpolator" is not officially documented in the above
           // link, but several support library aar files use it.
-          "interpolator");
+          "interpolator",
+          // "transition" is not documented in the above link,
+          // but the docs below claim it can be used
+          // https://developer.android.com/reference/android/transition/Transition
+          "transition");
 
   /**
    * Represents the names and values of valid densities for resources as defined in

test/com/facebook/buck/android/testdata/android_project/res/com/sample/base/res/transition/some_transition.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<transitionSet xmlns:android="http://schemas.android.com/apk/res/android">
+  <explode
+    android:duration="320" />
+</transitionSet>