saber should come with one 'default' dataset

[JohnGiorgi]

It would be useful if saber came with a default dataset (pointed to by the default config file). This would make it easier to follow along with the notebook (which currently serves as documentation) or the readme directly after installing saber.

No idea how to reference files internally in the config.ini file though. Asked a question on stackoverflow to get some help: https://stackoverflow.com/questions/52391209/specify-relative-filepath-in-ini-file-with-pythons-configparser