Pass dataset by URL

Input: http://netflower.fhstp.ac.at/app.html?data=https://dl.dropboxusercontent.com/s/9l44stgudtrt9fz/zwr_person_to_person_per.csv?dl=0

- in data_import.ts
- Check if URL has a data parameter.
- Possible decode URL
- call this.handleFileUrl(urlInput);