Retry download if ITC stats not available, and a new PHP based web page with graphs

Here are two changes for you to consider.

* I have noticed that sometimes ITC data is not available until fairly late in the day, meaning that if you call this script in cron, sometimes the stats for that day are not available yet.  I have tweaked the `update.sh` script to retry the download every hour until it is available using the `at` command.
* I have added a new PHP based web page that displays the graphs using the [JpGraph](http://jpgraph.net/) library.  This is pretty rough (basically a 5 minute hack job) but works surprisingly well, and is great for when you want to check your graphs from outside of Status Board.