Move drawing of ports into main.js

This reduces the number of .js which are pulled by the browser
when loading a http page, which should reduce the loading time.
Also prepare for device-dependent logical to physical port
mappings.

html/lag.html

@@ -1,6 +1,5 @@
 <!DOCTYPE html>
 <html>
-  <script src="/ports.js"></script>
   <script src="/main.js"></script>
   <link rel="stylesheet" href="style.css">
   <title>Link Aggregation Configuration</title>