Add more local datasets

[jakevdp]

We can add local datasets if

• the dataset license is compatible with the package MIT license (this is often tough to figure out, because the provenance of many available datastes is unclear)
• the dataset is small enough that it won't significantly affect the package size

Adding a dataset to the package is easy:

• add the name to the list at https://github.com/jakevdp/vega_datasets/blob/master/tools/download_datasets.py#L17
• add dataset description & references (including license if available) to https://github.com/jakevdp/vega_datasets/blob/master/vega_datasets/dataset_info.json
• run python tools/download_datasets.py
• commit the downloaded datasets & modified descriptions & open a Pull Request

[iliatimofeev]

Does the CC BY 4.0 compatible with MIT?
I would like to add some examples based on gapminder or world bank data, both sources under CC BY 4.0 is it possible?

[jakevdp]

Hmm... I think so? In any case the datasets need to be part of http://github.com/vega/vega-datasets/ before they can be included here.