Add a basic, empty spline UI based on Angular

The page doesn't do anything yet, but should let people build up a
more complex UI.

This is effectively a super stripped down version of the scouting app.

Signed-off-by: Philipp Schrader <philipp.schrader@gmail.com>
Change-Id: Ia97a3670439f4c3f208f8110282645aa0e3862f1
diff --git a/tools/build_rules/js.bzl b/tools/build_rules/js.bzl
index d7096a9..a95d5f2 100644
--- a/tools/build_rules/js.bzl
+++ b/tools/build_rules/js.bzl
@@ -84,8 +84,8 @@
       assets: assets to include in the file bundle
       visibility: visibility of the primary targets ({name}, 'test', 'serve')
     """
-    assets = assets if assets else native.glob(["assets/**/*"])
-    html_assets = html_assets if html_assets else []
+    assets = assets if assets != None else native.glob(["assets/**/*"])
+    html_assets = html_assets or []
 
     test_spec_srcs = native.glob(["app/**/*.spec.ts"])