validate-ptolemy cron job

A cron job has been started on lore.genomecenter.ucdavis.edu to run 'ant validate-ptolemy' every midnight. The revision.txt commits should be a few minutes after, by SVN user 'riddle'. There were some issues with making the ant target send an email when the command fails. Where to place code that is executed in response to an error at any point along the pipeline (updating modules, compilation, committing revision.txt, etc.) and taking uniform action is not clear.

The code to send the email is, however, already written, so if anyone wants to investigate ant and figure out how to process the different types of errors, they are welcome to.

Since this cron job approach has had problems before, logs are maintained and rotated with logrotate. The logs are located at /home/sean/ptolemy-validation/ (on lore), and can be viewed by any user in the sudo group (Sean Riddle, Daniel Zinn, Sven Koehler, at the moment).