Move res files to be more gradle-esque

Summary: Resources don't usually live under the package name.  We want to gradle build this soon, so making the directory structure as traditional as possible is best.

Reviewed By: emilsjolander

Differential Revision: D4557978

fbshipit-source-id: 7f80599201fe007a895e52bc5141425f9a83eb51

android/sample/BUCK

@@ -17,6 +17,15 @@ android_binary(
   ],
 )
 
+android_resource(
+  name = 'res',
+  res = 'res',
+  package = 'com.facebook.samples.yoga',
+  visibility = [
+    'PUBLIC',
+  ],
+)
+
 keystore(
     name='debug_keystore',
     store='debug.keystore',