Update the data files of the hosted datasets using the new `gli.io` functions

[jiaqima]

Is your feature request related to a problem? Please describe.

We have added some restrictions on the naming format for data files and plan to get rid of urls.json (see #425). As a result, we will need to update all the hosted datasets to ensure they comply the new change.

Describe the solution you'd like

1. Change the jupyter notebook in each dataset to utilize the new gli.io functions to save both the json files and the data files for the graph and the tasks.
2. Upload the new data files to Dropbox.
3. Remove the urls.json and push the changes to the repo.

Additional context

See #425 (comment)