Remove the web app and create export script

The web app could use more love than I am able to give it and so this is a way for me to get access to the data in a more reliable format without having to dedicate myself to a useless app.
Display the festivals when no files are specified
Rename "ext" folder
Create a sources directory for data sources

This is in preparation for fetching from multiple sources.
Add Last.FM source

I also removed the `update.js` file as it is no longer used.
Add argument for selecing source
Update readme with @todo section