Add celery beat startup script
Add build expiry configuration
Adds a periodic build cleanup method
Add a job to parse out the revision and timestamp info from the 'svn info' command
Ensure the SVN info is up to date with a new checkout
Cleanup task.py
Add build timestamp info
Configure a periodic build directory cleanup
Update svn info on app startup
Remove dependency on shelve

Persistence is through a file.
Update gitignore