[CORE] Move public resources to a /public directory

Advantages:
* Increases security by preventing direct access to file/
* We are careful and have a defined('GNUSOCIAL') || die() to prevent
  direct access to GS files, but we may miss one or a vendor/extlib may
  not be as careful
* Improves directory structure - It's more natural to physically
  separate what is public from what are GNU social resources

plugins/Comet/js/cometupdate.js

@@ -1,27 +0,0 @@
-// update the local timeline from a Comet server
-var CometUpdate = function()
-{
-     var _server;
-     var _timeline;
-     var _userid;
-     var _replyurl;
-     var _favorurl;
-     var _deleteurl;
-     var _cometd;
-
-     return {
-          init: function(server, timeline, userid, replyurl, favorurl, deleteurl)
-          {
-               _cometd = $.cometd; // Uses the default Comet object
-               _cometd.init(server);
-               _server = server;
-               _timeline = timeline;
-               _userid = userid;
-               _favorurl = favorurl;
-               _replyurl = replyurl;
-               _deleteurl = deleteurl;
-               _cometd.subscribe(timeline, function(message) { RealtimeUpdate.receive(message.data) });
-               $(window).unload(function() { _cometd.disconnect(); } );
-          }
-     }
-}();