Automate scanning of Comics directory

[hmhrex]

Just as the label says.

Some notes: http://timgolden.me.uk/python/win32_how_do_i/watch_directory_for_changes.html https://thomassileo.name/blog/2013/12/12/tracking-changes-in-directories-with-python

[hmhrex]

It would also makes sense to move scraping from a controller to Celery. This way the processing can happen in the background while the user can still read comics that are already loaded.