Example notebooks need to be updated for 1.0

Some example notebooks break after the 1.0.0-Beta2 release.
We need to fix the notebooks in /examples/dev and update them to the /examples folder with working dataframe/kandy versions, so people can get started more easily :)

@kikoso feel free to create a PR with fixes for the german companies notebook. Thanks for the help and for your talk at KotlinConf! :)