Use another `slug` function

[turicas]

The slug function implemented in rows is simple and effective but may not work for other alphabets.
We should consider using one of the following libraries:

• unicode-slugify
• python-slugify
• awesome-slugify

[turicas]

Check if can convert text like these: http://www.w3.org/TR/2015/WD-tabular-data-model-20150416/#bidirectionality-in-csv-files