Update regular expression: DATASET_KEY_PATTERN

[Wilfongjt]

The current DATASET_KEY_PATTERN expression doesn't match dataset names that use underscores. GR-drains is ok but GR_drains breaks the match. Data.world supports underscores and hyphens.

[rflprr]

Hi, @Wilfongjt.

data.world doesn't allow underscores. As you can see in the example below, if I attempt to create a dataset named GR_drains under my rflprr account, the URL for it will automatically be established as https://data.world/rflprr/grdrains, where rflprr/grdrains is the dataset key.

Let me know in case this doesn't make sense. If you are still having trouble, let me now what you are trying to accomplish and I will try to help.