Better naming for imported datasets

[mohammad-alisafaee]

When importing a dataset, we create a dataset name (slug) using title of the dataset and its version which contains only alphanumeric characters. This is a bit confusing in the version part because we remove separator dots from version (e.g. 1.0 becomes 10).

renku dataset import -y 10.7910/DVN/WTZS4K
ls data  # 201901_us_flights_10

We should keep the dots in version part; for example the above name will be 201901_us_flights_1.0.