Depend on config rule instead of file.

The aos_config rule used to require you to depend on {name}.json to get
the output.  That was weird and hid private/testonly/etc.  Instead,
depend on the rule directly.

Change-Id: I1596a6c1f44b246a0db1bbc562468530a0b69614
diff --git a/y2016/BUILD b/y2016/BUILD
index a96ea5a..190e0e0 100644
--- a/y2016/BUILD
+++ b/y2016/BUILD
@@ -52,7 +52,7 @@
 
 robot_downloader(
     data = [
-        ":config.json",
+        ":config",
     ],
     dirs = [
         "//y2016/dashboard:www_files",