Frontend now build on top of home-assistant-js

scripts/dev_js

@@ -0,0 +1,9 @@
+# If current pwd is scripts, go 1 up.
+if [ ${PWD##*/} == "scripts" ]; then
+    cd ..
+fi
+
+cd homeassistant/components/frontend/www_static/polymer/home-assistant-js
+
+npm install
+npm run dev