File Deletion

[agilgur5]

Delete files when a user closes the browser (before unload? or perhaps back end catch).

[agilgur5]

There doesn't seem to exist a back end catch in the default session because it's cookie based (and therefore client side)... Before unload would likely work, though shouldn't be something to rely on for deletion. Would be better to either use temp files or delete files every 24 hours
http://librelist.com/browser//flask/2013/2/2/how-to-do-server-side-cleanup-on-session-expiration/#0b449dbbc32854699adf4ab3767da079

[agilgur5]

Latest commit adds async deletion of files older than 24 hours whenever a session is created.
Note: If there are many users, local storage on Heroku will likely break. CDN/S3 should technically be used if there any plans on scaling

[agilgur5]

Need to delete directories now as well because of changes to #4
http://stackoverflow.com/questions/2237909/delete-old-directories-in-python
http://stackoverflow.com/questions/13769008/get-all-folders-os-walk-that-are-older-than-x-days-delete